[The value of integrated PET-CT images in 2 lymphoma patients with skeletal localisations]. / De waarde van gefuseerde PET-CT-beelden bij 2 lymfoompatiënten met skeletlokalisaties.

In two women with Hodgkin's disease, 36 and 34 years of age, the PET-scan showed increased FDG-uptake in regions where the CT-scan did not reveal any abnormalities. Integration of the PET-CT images visualised bone marrow localisations in both patients. One patient underwent a CT-guided bone biopsy that confirmed this localisation. In both cases, the results of the integrated PET-CT images altered the therapy that would have been given on the basis ofthe standard staging technique. Both patients underwent radiotherapy. After 6 months, one patient had no visible lesions. The other patient died due to progression ofthe disease. Integrated PET-CT images can play an important role, not only in the precise classification and staging of lymphoma but also at the start of therapy, as an initial scan, in the evaluation of the response to treatment, and in the early detection of recurrence.

Medullary cone movement in subjects with a normal spinal cord and in patients with a tethered spinal cord.

PURPOSE: To compare movement of the normal medullary cone when the patient has changed from a supine to prone position with that in patients with known or suspected tethered spinal cord syndrome. MATERIALS AND METHODS: Fifty-six individuals divided into three groups were examined with lumbar spine magnetic resonance (MR) imaging performed with the patient in the prone and supine positions. Group 1 consisted of 15 healthy volunteers and six patients with a herniated disk; group 2, 25 patients clinically suspected of having a tethered cord; and group 3, 10 patients who previously had undergone tethered cord surgery. RESULTS: All group 1 subjects showed distinct and statistically significant medullary cone movement (range, 21%--41%); no patient in group 3 showed movement (Wilcoxon rank sum test, P <.001). In group 2, the 20 patients in whom a definite diagnosis of tethered cord syndrome was made on the basis of initial supine MR image findings showed no movement, whereas two of five patients with normal supine MR images had abnormal and decreased cone movement at prone imaging. CONCLUSION: Prone MR imaging has no additional value when the supine MR image has clearly shown the cause of tethering or in patients who have undergone tethered cord surgery, but it can provide additional information in patients clinically suspected of having a tethered cord and in whom supine MR imaging depicted no abnormalities.

Antegrade ureteral stent placement: positioning without use of a retraction string.

PURPOSE: To evaluate a simple method of antegrade ureteral stent insertion allowing optimal positioning of the stent without the use of a retraction string. PATIENTS AND METHODS: Seventeen stents were placed in sixteen patients with ureteral obstruction. Materials included a long vascular introducer sheath and radiopaque markers on the tips of both the sheath and the pusher catheter. For optimal positioning of the proximal pigtail in the renal pelvis, the distal end of the sheath was used to hold a large portion of the pigtail in the extended state prior to its deployment. RESULTS: All stent placements were successful. In one case, the tip of the proximal pigtail was caught in a lower-pole calix. In another case, repeat stent placement was necessary because of recurrent stricture several months after removal of the first stent. All stents functioned properly, as demonstrated by follow-up nephrostography 2 or 3 days after each procedure. CONCLUSION: The insertion method we describe is simple, easy to perform, and fast and avoids the risks associated with the use of a retraction string.

Advances in three-dimensional diagnostic radiology.

The maturity of current 3D rendering software in combination with recent developments in computer vision techniques enable an exciting range of applications for the visualisation, measurement and interactive manipulation of volumetric data, relevant both for diagnostic imaging and for anatomy. This paper reviews recent work in this area from the Image Sciences Institute at Utrecht University. The processes that yield a useful visual presentation are sequential. After acquisition and before any visualisation, an essential step is to prepare the data properly: this field is known as 'image processing' or 'computer vision' in analogy with the processing in human vision. Examples will be discussed of modern image enhancement and denoising techniques, and the complex process of automatically finding the objects or regions of interest, i.e. segmentation. One of the newer and promising methodologies for image analysis is based on a mathematical analysis of the human (cortical) visual processing: multiscale image analysis. After preprocessing the 3D rendering can be acquired by simulating the 'ray casting' in the computer. New possibilities are presented, such as the integrated visualisation in one image of (accurately registered) datasets of the same patient acquired in different modality scanners. Other examples include colour coding of functional data such as SPECT brain perfusion or functional magnetic resonance (MR) data and even metric data such as skull thickness on the rendered 3D anatomy from MR or computed tomography (CT). Optimal use and perception of 3D visualisation in radiology requires fast display and truly interactive manipulation facilities. Modern and increasingly cheaper workstations ( < $10000) allow this to be a reality. It is now possible to manipulate 3D images of 256 at 15 frames per second interactively, placing virtual reality within reach. The possibilities of modern workstations become increasingly more sophisticated and versatile. Examples presented include the automatic detection of the optimal viewing angle of the neck of aneurysms and the simulation of the design and placement procedure of intra-abdominal aortic stents. Such developments, together with the availability of high-resolution datasets of modern scanners and data such as from the NIH Visible Human project, have a dramatic impact on interactive 3D anatomical atlases.

Value of sinus radiographs in the diagnosis of maxillary sinus disease: interobserver agreement on sinus radiographs by otolaryngologists and radiologists.

Variability between observers and specificity of sinus radiographic findings are subject to discussion. The aim of this study was to assess interobserver variability, between four physicians, two otolaryngologists and two radiologists, in the evaluation of 100 maxillary sinus radiographs. Equal agreement was found within the specialties when rating radiographs as normal or abnormal (80%). Kappa values for interobserver agreement were 0.45 for otolaryngologists and 0.58 for radiologists, both representing fair to good agreement. Otolaryngologists reported more abnormalities (67 vs, 57). Agreement on specific findings (complete opacity, fluid level and mucosal swelling) was fair to good (kappa values between 0.38 and 0.83). Agreement between the four physicians was lower on all outcomes. It is concluded that interobserver variability is within acceptable limits and justifies the continued use of conventional sinus radiographs for confirmation of maxillary sinus disease.

Lenticular system: full-color, limited-angle, autostereoscopic alternative to holography.

The microlenticular system is a method of hard copy imaging that provides stereoscopic cues without the use of special glasses or viewing devices. Therefore, it is called an autostereoscopic technique. The microlenticular system consists of a layer of cylindric lenses combined with a photographic emulsion that carries three to seven different two-dimensional views of the same three-dimensional (3D) scene. Since each of the observer's eyes sees a different view, the resulting image is perceived as being 3D. The microlenticular system technique can be traced back to 1908 but was recently revived because of inventions that allow automatic photographic printing of this type of hard copy. The technique has been applied to visualization of medical 3D images obtained with the following modalities: computed tomography (CT), magnetic resonance imaging, single photon emission CT, ultrasound, scanning electron microscopy, laser scanning, and confocal laser microscopy. Use of this technique results in images suitable for planning complex surgery and for simplifying the communication of complex geometries in science and education.

Screening for bronchiectasis. A comparative study between chest radiography and high-resolution CT.

STUDY OBJECTIVE: The aim of our study was to investigate whether in the search for bronchiectasis a correlation exists between abnormalities on the chest radiograph and high-resolution CT (HRCT), and if HRCT has an additional value when the chest radiography is normal. SUBJECTS AND METHODS: In a prospective study, chest radiographs were compared with HRCT in 84 patients. Analysis of presence and extent of bronchiectasis were made for each bronchopulmonary lobe. RESULTS: Thirty-seven patients had a normal radiograph, from whom 32 had a normal HRCT. The other 5 had a low HRCT severity score with a mild cylindrical bronchiectasis. From the 47 patients with an abnormal radiograph, 36 had signs of bronchiectasis at HRCT; 11 patients, however, had a normal HRCT. The sensitivity for chest radiography to detect bronchiectasis appeared to be 87.8% with a specificity of 74.4%. We found a significant linear relationship between the severity of bronchiectasis at HRCT and abnormalities as seen on the chest radiograph (r=0.62, p=0.0001). CONCLUSION: A normal chest radiograph almost always excludes relevant bronchiectasis and no further investigation seems necessary. There is a significant linear relationship between the severity of bronchiectasis at HRCT and abnormalities as seen on the chest radiograph.

Clinical safety and efficacy of iobitridol in urography.

PURPOSE: Evaluation of imaging quality and safety of iobitridol 300 compared to iohexol 300 in urography. MATERIALS AND METHODS: 180 patients were included in an urography multicenter study (3 centers, 60 patients in each). RESULTS: There was no significant difference in either the imaging quality or the clinical safety between the 2 contrast media groups. CONCLUSION: Iobitridol is a safe and efficient contrast agent in urography.

Assessment of bronchiectasis: comparison of HRCT and spiral volumetric CT.

OBJECTIVE: Our goal was to ascertain the sensitivity of spiral CT for the detection of bronchiectasis in comparison with high resolution CT (HRCT). MATERIALS AND METHODS: Thirty-one patients with a suspected clinical diagnosis of bronchiectasis were evaluated with spiral CT (slice thickness 5 mm, pitch 1, reconstruction index 2 mm, 1 s rotation) and HRCT (1.5 mm, interval 10 mm). Analysis of the presence, type, and severity of bronchiectasis was performed for each bronchopulmonary lobe. RESULTS: In 30 patients, 177 lobes were evaluated. At HRCT 14 patients showed signs of bronchiectasis in 32 lobes. Spiral CT confirmed the presence in 29 lobes. In one lobe spiral CT was false positive. The severity score was the same in 23 lobes, in 4 lobes higher at HRCT, and in 2 lobes higher at spiral CT. Spiral CT has a high sensitivity of 91% to detect bronchiectasis with a specificity of 99.3%. Spiral CT demonstrates adequately lack of tapering of the bronchus. CONCLUSION: In patients with suspected bronchiectasis, HRCT is the method of first choice based on greater sensitivity and lower radiation dose. However, spiral CT done for other indications is a reliable method for assessment of bronchiectasis. Inability of patients to hold their breath did not prove to interfere with diagnostic reliability.

Radiation exposure in standard and high-resolution chest CT scans.

It has been suggested that radiation doses due to high-resolution computed tomography (HRCT) of the chest are considerably higher than those from conventional CT. We compared the effective dose (E, mSv) in conventional chest CT (10-mm contiguous slices) and HRCT (1.5-mm slices, gap 10 mm). In our study, the effective dose from a HRCT (0.98 mSv) is about 6.5 times less than the effective dose from a standard CT scan (6.5 mSv), and only a factor 12 higher than from a conventional chest examination (0.085 mSv).

Dynamic rectal examination (defecography).

Dynamic rectal examination (DRE), first described in 1952, is becoming more widely used in the dynamic evaluation of pelvic floor and anorectal motility disorders. It is a minimally invasive investigation which is well tolerated by patients and provides information about the anosphincteric, puborectal and levator muscle in addition to insight in rectal function and structure. DRE is the only investigation of anorectal function that can give detailed anatomical information such as the presence of a rectocele, an enterocele and an intussusception. DRE should be performed in a quiet environment with a minimum number of investigators present. Any technique which attempts to study the defecatory mechanism must be a compromise since the patient is aware of being studied. In order to defecate on command the radiologist must make the patient comfortable before starting the investigative procedures to avoid any possible psychological inhibition. We have not encountered any failures in this regard. The relative value of the radiological findings with respect to symptoms and complaints is insufficiently known. This has been the main incentive to design carefully and carry out a large prospective critical evaluation of various aspects of DRE in particular the correlation with objective findings and symptoms. Moreover an assessment has been made of its overall clinical utility (Wiersma, 1994). It is very likely that DRE is both investigator- and technique-dependent. To ensure that the study is as physiological as possible the contrast medium used to fill the rectum needs to be semi-solid and malleable equivalent in consistency to a normal faecal bolus. For proper anatomical studies in females vaginal opacification is mandatory. The acceptance of vaginal contrast was good. Only 4% of the female patients preferred not to have the vaginal application of contrast. The technique of DRE when performed with small bowel and vaginal opacification provides a sensitive and objective method of detecting enteroceles. A substantial number of female patients related the onset of their complaints to hysterectomy. In female patients with constipation there was a significantly higher incidence of enteroceles in patients with a hysterectomy compared to the group of females without hysterectomy. Because of these findings a series of pre- and postoperative DREs in hysterectomy patients are on their way in our institute. Unlike a rectocele which is usually most obvious during defecation, enteroceles are sometimes appreciated only with repeated straining after evacuation.(ABSTRACT TRUNCATED AT 400 WORDS)

Cerebral visual impairment in cerebral palsy: relation to structural abnormalities of the cerebrum.

In patients with cerebral palsy (CP), cerebral visual impairment (CVI) is frequently found in addition to ophthalmological disorders. Lesions in the visual areas are found in CT scans of CP patients with CVI. The aim of the present study was to determine the prevalence of these specific findings in CP patients with CVI. CT scans of 49 cerebral palsy patients were studied; CVI was diagnosed in 36 patients; in 13 patients, visual acuity was normal. In 8 patients, comparison with an MRI scan was possible (6 with CVI, 2 with normal acuity). The CT scans were scored according to the criteria used by Van Nieuwenhuizen (1987): normal, abnormalities of the white matter adjacent to the posterior horns of the lateral ventricles, abnormalities of the white matter located under the visual cortex, abnormalities of the visual cortex and abnormalities elsewhere. Abnormalities in the visual areas were found in 15% of the normal acuity group and in 53% of the CVI group. In 17 of the 19 CVI patients with abnormalities in the visual areas, the lesions were located in the white matter surrounding the posterior horns (89%). MRI imaging revealed the same abnormalities as the CT scans in 6 patients, but in one patient the abnormality was seen in more detail and in one patient the lesion in the occipital area was seen only on MRI. MRI examination seems to detect at least as many, but in some cases even more specific lesions in CVI patients compared to CT scanning, but the numbers were too small to allow any definitive conclusions to be drawn.

[Selection of medical residents for medical specialist education: experiences with a structured procedure]. / Selectie van assistent-geneeskundigen voor medisch-specialistische opleidingen: ervaringen met een gestructureerde procedure.

OBJECTIVE: Evaluation of an objective, standardised method for selection of residents for medical specialty training. DESIGN: Retrospective. SETTING: University Hospital Utrecht, department of diagnostic radiology. Utrecht University, Department of Clinical Psychology and Health Psychology. METHODS: All applicants for residency positions in 1990-1991 were requested to complete a standard application form. The applications were judged by seven staff members on six criteria. Using statistical tests the relative contribution of each criterium was calculated. A similar procedure was followed for those who were invited for an interview. RESULTS: Most of the criteria applied for the written and oral applications contributed significantly to the rank order achieved. The written and oral criteria showed some degree of overlap, whilst the criteria used for the written application were relatively independent from those used for the interview. For a balanced evaluation of the written information a selection committee of four staff members was sufficient. CONCLUSION: Structuring the selection process as described gives both staff and applicants more insight in the criteria applied, and thus allows a more objective and valid evaluation. To medical students it is beneficial to become acquainted with criteria that may be used in selection procedures for medical specialty training, so they can prepare themselves adequately.

Head and neck tumors, MRI versus CT: a technology assessment pilot study.

Thirty-three patients with head and neck tumors were evaluated with both magnetic resonance imaging (MRI) and high-resolution computed tomography (HRCT). Although CT and MRI of the head and neck are well-established clinical methods, reports assessing the relative value of both modalities are not available. Technology assessment was based on the determination of how often and to what extent MRI versus CT provided valuable diagnostic information, and whether this information influenced patient management. The diagnostic values were classified in five groups, ranging from confusing to unique information. Therapeutic values were classified in five groups ranging from disadvantageous therapy, to a favorable change of treatment. All benign tumors found in 14 patients showed positive diagnostic and therapeutic results with MRI (100%). In 19 cases of malignancy a positive yield of 84% was found in the diagnostic and therapeutic results. Two of six squamous cell carcinoma and one of two rhadbomyosarcomas had a negative therapeutic value. As MRI played a positive role in therapeutic management in 91% of the examinations, it is the method of choice for therapy planning and follow-up of head and neck neoplasm. However, when skull base infiltration is suspected, CT is preferred. MRI provides valuable information to support diagnosis of the disease.

Occluding staghorn calcification of the aortic arch and left subclavian artery: case report.

A calcified thrombus resembling a staghorn was found in the aortic arch, cast into this shape by the aorta and its branching vessel, the left subclavian, into which it projected for a short distance. Unique, in this case, is the extraordinarily large size of the calcification which was mostly free of the vessel wall, its radiological image, and its location. Digital subtraction angiography led to the diagnosis and was confirmed on computed tomography.