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Biomedical subjects

J M van Engelshoven

Publications and source records attributed to J M van Engelshoven.

At least 19 recordsLinked to original sources
PubMed2003

[The limited detection of lung cancer on chest X-rays].

In a study of everyday clinical practice, the diagnosis 'lung cancer' was not made on the chest X-ray initially in one-fifth of the cases, even though in retrospect the lesions had been visible on the chest X-ray. In nearly half of these cases, the diagnosis had been missed at least twice on succeeding X-rays of the patient in question. Most often, superimposed structures are responsible for having missed lesions on the chest X-ray; this was the case in 71% of the patients in whom a lesion was missed. The intra- and inter-observer variation in the detection of small tumours on the chest X-ray are quite large (kappa: 0.38 and 0.48, respectively). Providing clinical information or previous chest X-rays for purposes of comparison does not improve the observer performance. Separate evaluation by two assessors ('double reading') also does not improve the results significantly. Simultaneous evaluation ('dual reading') improves the sensitivity slightly (from 28 to 37%), but has hardly any effect on the specificity (from 93 to 92%), thus improving the results somewhat. The results with computed tomography are much better (high sensitivity but low specificity). A CT-scan of the chest seems indicated in case of a suspicion of lung cancer and/or when there is a (slight) suspicion of lung cancer on the basis of the chest X-ray.

Humans↗
PubMed2001

Diagnostic tests for renal artery stenosis in patients suspected of having renovascular hypertension: a meta-analysis.

PURPOSE: To summarize and compare the validity of computed tomography angiography, magnetic resonance angiography, ultrasonography, captopril renal scintigraphy, and the captopril test for diagnosis of renal artery stenosis in patients suspected of having renovascular hypertension. DATA SOURCES: For each diagnostic modality, published studies were identified by MEDLINE literature searches. STUDY SELECTION: Original studies were selected if they met the following criteria: 1) suspicion of renovascular hypertension was the indication for the test; 2) intra-arterial x-ray angiography was used as the gold standard; 3) a cutoff point for a positive test result was explicitly defined; and 4) absolute numbers of true-positive, false-negative, true-negative, and false-positive results were available or could be derived from the presented data. DATA EXTRACTION: A standard form was used to extract relevant data. DATA SYNTHESIS: Data on the accuracy of the different diagnostic methods were analyzed and compared by constructing summary receiver-operating characteristic (ROC) curves and by computing areas under the summary ROC curves. RESULTS: Although accuracy varied greatly for all diagnostic modalities, summary ROC curves found that computed tomography angiography and gadolinium-enhanced, three-dimensional magnetic resonance angiography performed significantly better than the other diagnostic tests. CONCLUSIONS: Computed tomography angiography and gadolinium-enhanced three-dimensional magnetic resonance angiography seem to be preferred in patients referred for evaluation of renovascular hypertension. However, because few studies of these tests have been published, further research is recommended.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Diagnostic value of radiological breast imaging in a non-screening population.

The aim of this study was to assess the diagnostic performance of breast imaging in the diagnosis of breast cancer in a non-screening population. In a consecutive set of patients referred for mammography in one year, the results of palpation and radiological breast imaging were scored on a 5-point grading scale and linked to pathology as gold standard after a follow up period of one year. The diagnostic performance was studied by logistic regression analysis and ROC-curves. There were 1,944 breast examinations in 1,890 patients and 3,816 breasts. Pathology results reported 118 malignancies in 115 women. With a cut-off point between benign and uncertain benign a sensitivity of 89% and a specificity of 98% was found for radiological imaging. ROC-curves showed a significant increase in diagnostic performance when radiology was added to results of palpation and age (p = 0.007). Radiological imaging tests have a large diagnostic value in the detection of breast cancer in addition to palpation and age. A sensitivity close to 100% could be reached.

Adolescent↗
PubMed2001

Accuracy of magnetic resonance imaging in prediction of tumour-free resection margin in rectal cancer surgery.

BACKGROUND: Incomplete surgical removal of the circumferential tumour spread is believed to be the main cause of local recurrence after resection of rectal cancer. This study assessed the accuracy of magnetic resonance imaging (MRI) with a phased-array coil for preoperative staging and prediction of the distance of the tumour from the circumferential resection margin in a total mesorectal excision. METHODS: 76 patients with primary rectal cancer were preoperatively assessed by MRI at 1.5 T, with a phased-array coil. Two observers independently scored, on two occasions, the tumour stage and measured the distance to the mesorectal fascia. Their findings were compared with the final histological findings. FINDINGS: The MRI tumour stage agreed with the histological stage in 63 (83%) of 76 patients (weighted kappa=0.77 [95% CI 0.66-0.89]) for observer 1, and in 51 (67%) patients (weighted kappa=0.52 [0.37-0.67]) for observer 2. The intraobserver agreement on the tumour stage was good (kappa=0.80 [0.69-0.91]) for observer 1 but moderate (kappa=0.49 [0.34-0.65]) for observer 2. The interobserver agreement was moderate (kappa=0.53 [0.38-0.69]). In 12 patients with an obvious T4 tumour, a margin of 0 mm was correctly predicted. Of 29 patients for whom the pathologist reported a distance of at least 10 mm without specifying the actual distance, a distance of at least 10 mm was predicted in 28 by observer 1 and 27 by observer 2. For the remaining 35 patients, a regression curve was constructed; from this, a histological distance of at least 1.0 mm can be predicted with high confidence when the measured distance on MRI is at least 5.0 mm. INTERPRETATION: MRI with a phased-array coil showed moderate accuracy and reproducibility for predicting the tumour stage of rectal cancers. The clinically more important circumferential resection margin can, however, be predicted with high accuracy and consistency, allowing preoperative identification of patients at risk of recurrence who will benefit from preoperative radiotherapy, more extensive surgery, or both.

Adult↗
PubMed2001

Need for background suppression in contrast-enhanced peripheral magnetic resonance angiography.

To determine if background suppression is beneficial for peripheral magnetic resonance angiography (pMRA), nonsubtracted, subtracted, and fat-saturated contrast-enhanced (CE) pMRA were compared in 10 patients with peripheral arterial disease. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs), as well as venous enhancement and subjective interpretability, were determined in a station-by-station fashion for each technique. In three patients X-ray angiography was available as a standard of reference. SNRs and CNRs were significantly higher for fat-saturated vs. the other two techniques (P = 0.005). Subjective interpretability was best for subtracted data sets in the lower-leg station. In the iliac station, fat-saturated data sets were considered to have significantly lower interpretability than subtracted data sets. Venous enhancement occurred significantly more often in the lower-leg station with the fat-saturated technique. The value of subtraction depends on the hardware one has available and is a useful tool if dedicated surface coils are used. Background suppression by means of magnitude subtraction leads to the best lower-leg image interpretability. Care must be taken to avoid venous enhancement in the lower-leg station when using fat saturation.

Arterial Occlusive Diseases↗
PubMed2001

Movement correction of the kidney in dynamic MRI scans using FFT phase difference movement detection.

To measure cortical and medullary MR renograms, regions of interest (ROIs) are placed on the kidney in images acquired using dynamic MRI. Since native kidneys move with breathing, and breath-holding techniques are not feasible, movement correction is necessary. In this contribution we compare three correction methods, based on image matching, phase difference movement detection (PDMD), and cross-correlation, respectively. The PDMD-based method showed the best performance and was able to determine kidney movement in our test series in 68% of the scans with no visible deviation, and in 88% of the scans if a one-pixel deviation is considered acceptable.

Algorithms↗
PubMed2001

MR renography by semiautomated image analysis: performance in renal transplant recipients.

We evaluated a method of semiautomated analysis of dynamic MR image series in renal transplants. Nine patients were studied twice, with an average time interval of 7 days. MR examination consisted of a run of 256 T1-weighted coronal scans (GE; TR/TE/flip: = 11/3.4/60 degrees; slice thickness = 6 mm; temporal resolution = 2 seconds). Gadolinium-DTPA (0.05 mmol/kg) was injected with an injector pump (5 ml/seconds). MR renographs of the cortex and medulla were obtained by segmentation of the renal transplant and placement of two regions of interest (ROIs) overlying the peripheral and central renal parenchyma. In the first 100 frames of the renographs, analysis of variance (ANOVA) demonstrated significant intraclass correlation coefficients with mean values for the cortex and medulla of 0.47 and 0.59, respectively. We conclude that the procedure is a robust technique that generates meaningful signal curves.

Contrast Media↗
PubMed2001

Detection of lung cancer on the chest radiograph: a study on observer performance.

STUDY OBJECTIVES: to study the validity and observers consistency in the detection of lung cancer on the chest radiograph. MATERIALS AND METHODS: the chest radiographs of 100 clinical cases were interpreted by 14 observers. The radiographs were obtained from 30 patients with initially missed but histopathologically proven non-small cell lung cancer (NSCLC), 35 patients with other cardiopulmonary diseases and 35 patients with no abnormalities. The observers consisted of ten experienced radiologists, two-experienced chest physicians and two residents in radiology. All observers were unaware of the study design. The validity and observer consistency was determined for each observer. RESULTS: the mean sensitivity and specificity of the ten radiologists were 0.36 and 0.90. For the two chest physicians, the mean sensitivity and specificity were 0.29 and 0.96. For the two residents in radiology, mean sensitivity and specificity were 0.25 and 0.94. The mean interobserver kappa and mean intraobserver kappa for the radiologists were 0.38 and 0.54. For the two chest physicians, the mean interobserver kappa was 0.43, while the intraobserver kappa was 0.59. For the two residents in radiology, mean interobserver kappa was 0.35 and the intraobserver kappa was 0.42. There was no significant relation between the consistency parameters and validity parameters. The interobserver and intraobserver kappa values showed good correlation. CONCLUSION: the validity of the chest radiograph and observers consistency in the detection of nodular lung cancer varies widely. The level of experience is likely to influence the diagnostic performance.

Humans↗
PubMed2001

Detection of lung cancer on the chest radiograph: impact of previous films, clinical information, double reading, and dual reading.

To study the impact of clinical information, previous chest radiographs, double reading (one pair of observers read the films independently) and dual reading (one pair of observers read the films simultaneously) on the sensitivity, specificity and odds ratios of observers in the detection of early lung cancer on the chest radiograph. The study was performed in 3 sessions. In the first session, 14 observers reviewed the chest radiographs of 100 cases (30 with early lung cancer, 35 with no abnormalities, 35 with other cardiopulmonary diseases). Sensitivity, specificity, odds ratios and the effect of double reading were calculated. After 4 months, a second session was held in which 7 observers reviewed all cases with the provision of all information. The other 7 observers reviewed all cases without information again. To determine the effect of dual reading, in the third session, 4 pairs of observers reviewed all cases in which they disagreed in the first independent reading session. The effects of information, double reading and dual reading on sensitivity, specificity and odds ratio were calculated. The sensitivity of the observers in the first session ranged from 0.20 to 0.60 and the specificity from 0.87 to 0.95. In the second session, these parameters changed only slightly, independent from the availability of clinical information and previous films. With double reading the sensitivity increased and specificity decreased. With dual reading sensitivity increased and specificity remained unchanged. The odds ratios were improved with double reading by 4% and with the dual reading by 14%. Additional clinical information, previous chest radiographs, double reading and dual reading have little impact on the detection of early lung cancer on the chest radiograph.

Carcinoma, Non-Small-Cell Lung↗
PubMed2001

Anatomy of the anal canal and perianal structures as defined by phased-array magnetic resonance imaging.

BACKGROUND: The anatomy of the anal canal and perianal structures has been imaged using endoluminal magnetic resonance imaging (MRI). Phased-array MRI avoids the use of an endoluminal coil that may distort anatomy. The aim of this study was to describe the anatomy of the anal canal and perianal structures using phased-array MRI. METHODS: Imaging was performed in 14 men and 19 nulliparous women. The dimensions of the anal canal, puborectalis, external anal sphincter, perineal body, superficial transverse perineal muscle, bulbospongiosus, ischiocavernosus and anococcygeal body were measured in different planes, and sex differences were calculated. RESULTS: The lateral canal was significantly longer than its anterior and posterior part (P < 0.001). The anterior external anal sphincter was shorter in women than in men (P = 0.01) and occupied, respectively, 30 and 38 per cent of the anal canal length (P = 0.001). The caudal ends of the external anal sphincter formed a double layer. The perineal body was thicker in women than in men (P < 0.001) and easier to define. The superficial transverse muscles had a lateral and caudal extension to the ischiopubic bones. The bulbospongiosus was thicker in men than in women (P < 0.001). The ischiocavernosus and anococcygeal body had the same dimensions in both sexes. CONCLUSION: Phased-array MRI is a non-invasive technique that allows an accurate description of the normal anatomy of the anal canal and perianal structures.

Adult↗
PubMed2001

Teaching anatomy; a clinicians view.

The General Plan Anatomy as defined by the Netherlands Association of Anatomists and published in the European Journal of Morphology in 1999 is a good starting point for discussion between anatomists and clinicians to define what is indispensable anatomical knowledge for a competent physician. The plan to teach anatomy within a clinical context and to relate form and structure on function makes learning anatomy more attractive and will have a greater appeal for the student. The list of discipline-related objectives is too extensive for a general practitioner whereas parts of this list are too limited for related medical specialists. Teaching anatomy and teaching clinical sciences and expertise must become more integrated.

Anatomy↗
PubMed2001

Preoperative MR imaging of anal fistulas: Does it really help the surgeon?

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) imaging with a quadrature phased-array coil for the detection of anal fistulas and to evaluate the additional clinical value of preoperative MR imaging, as compared with surgery alone. MATERIALS AND METHODS: Fifty-six patients with anal fistulas underwent high-spatial-resolution MR imaging. Twenty-four had a primary fistula; 17, a recurrent fistula; and 15, a fistula associated with Crohn disease. MR imaging findings were withheld from the surgeon until surgery ended and verified, and surgery continued when required. RESULTS: MR imaging provided important additional information in 12 (21%) of 56 patients. In patients with Crohn disease, the benefit was 40% (six of 15); in patients with recurrent fistulas, 24% (four of 17); and in patients with primary fistulas, 8% (two of 24). The difference between patients with or without Crohn disease and between patients with a simple fistula versus the rest was significant (P <.05). The sensitivity and specificity for detecting fistula tracks were 100% and 86%, respectively; abscesses, 96% and 97%, respectively; horseshoe fistulas, 100% and 100%, respectively; and internal openings, 96% and 90%, respectively. CONCLUSION: High-spatial-resolution MR imaging is accurate for detecting anal fistulas. It provides important additional information in patients with Crohn disease-related and recurrent anal fistulas and is recommended in their preoperative work-up.

Adolescent↗
PubMed2001

Measurement of anal sphincter muscles: endoanal US, endoanal MR imaging, or phased-array MR imaging? A study with healthy volunteers.

PURPOSE: To compare endoanal ultrasonography (US), endoanal magnetic resonance (MR) imaging, and phased-array MR imaging for anal sphincter muscle measurement. MATERIALS AND METHODS: Sixty healthy volunteers underwent 1.5-T phased-array MR, endoanal MR, and endoanal US examinations. Sphincter muscle thicknesses were measured. Measurement reliability was analyzed, and correlations among the imaging methods were calculated. Multivariate analysis was performed to assess the influence of age, weight, height, sex, parity, and obstetric trauma on sphincter dimensions. RESULTS: Both MR methods had good reliability for measurements of all sphincter components, whereas endoanal US was reliable for internal sphincter measurement only. There was little correlation between the techniques, except between the two MR techniques, with a strong correlation for total sphincter and perineal body thickness. The internal sphincter thickened significantly (P =.002) with age at endoanal US and endoanal MR imaging but not at phased-array MR imaging. There were small sex-based differences in sphincter muscle measurements at phased-array MR imaging only. CONCLUSION: Endoanal US enables reliable measurement of only internal sphincter thickness, whereas both MR imaging methods enable reliable measurement of all sphincter components. Sphincter measurement with phased-array MR imaging is as reliable as that with endoanal MR imaging.

Adult↗
PubMed2001

Patient and occupational dosimetry in double contrast barium enema examinations.

A new and relatively simple method is presented to distribute total dose-area product (DAP) over a number of projections that model exposure during double contrast barium enema (DCBE) examinations. In addition, hitherto unavailable entrance and effective doses to the physician performing the DCBE examination have been determined. DAP, fluoroscopy time, number of images as well as some patient data were collected for 150 DCBE examinations. For a subset of 50 examinations, the distribution of DAP over 12 hypothetical but representative projections was estimated by measuring the entrance dose in the centre of each of these projections during the complete procedure. Effective dose to the patient was obtained using DAP to effective dose conversion coefficients calculated for each of the 12 projections. Exposure of the worker was quantified by measuring the entrance dose at the forehead, neck, arms, right hand and legs. The sex-averaged effective dose to the patient per examination was 6.4+/-2.1 mSv (mean+/-SD; n=50) and the corresponding DAP was 44+/-22 Gy cm(2). The effective dose to the worker per examination was 0.52 microGy (n=50), whereas the highest entrance dose of 30+/-25 microGy was found for the right arm. The proposed method for deriving the distribution of total DAP over a set of representative projections is much less time consuming than visual observation of patient exposure, whilst accuracy seems acceptable. Entrance and effective doses per examination for workers in DCBE examinations are very low. For a normal workload, doses remain far below the legally established dose limits.

Adult↗
PubMed2000

Reduction of noise in medullary renograms from dynamic MR images.

Dynamic magnetic resonance images of the kidney can be used to acquire separate renograms of the cortex and medulla. A high-quality cortical renogram can be determined directly from a region of interest (ROI) placed in the cortex. Due to partial volume effects, part of the signal from a ROI placed in the medulla is caused by cortical tissue. By subtracting a fraction of the cortical signal from the cortico-medullary signal, a purer medullary renogram can be obtained. A side effect of this subtraction is an increase in noise level. The noise level increases with larger partial volume fractions. Using a matched image filter, it is possible to exclude those areas from the ROI that have a high partial volume content, thus reducing the amount of cortical signal that has to be separated from the medullary signal. Noise reductions of up to 50% have been achieved in the medullary renogram, with an average reduction of 23%.

Contrast Media↗
PubMed2000

Three-dimensional contrast-enhanced moving-bed infusion-tracking (MoBI-track) peripheral MR angiography with flexible choice of imaging parameters for each field of view.

A technique to image peripheral arteries with flexible choice of scan parameters for separate stations was developed based on moving-bed single-bolus three-dimensional gradient-recalled echo magnetic resonance angiography. A volunteer study yielded higher signal- and contrast-to-noise ratios, less venous enhancement, and better subjective interpretability compared with imaging with fixed parameters for each station. Additionally, six patients were imaged to test the feasibility of the new method in a clinical setting. Imaging peripheral arteries with the new technique in volunteers yielded better image quality and is feasible for patients.

Adult↗