[Rotational angiography of the renal arteries].
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Angiography↗
Biomedical subjects
H M Klein
Publications and source records attributed to H M Klein.
[The cholegraphic effect of iopentol].
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Cholangiography↗
[The computed tomographic morphology of Crohn's disease and ulcerative colitis].
PURPOSE: To assess the value of computed tomography for the diagnosis of Crohn's disease and ulcerative colitis. METHOD: We analysed the CT examinations of 109 patients with 197 involved bowel locations. 81 patients suffered from Crohn's disease, 28 from ulcerative colitis. Diagnosis was based on the combination of clinical, endoscopic and histopathologic findings. Three radiologists evaluated the CT series concerning the presence of morphologic changes analogous to conventional radiographic findings. RESULTS: In Crohn's disease, we found irregular outer contours in 26% of cases. The bowel wall was thickened in 82%. In acute phases, the bowel wall was thickened in 100%. Abscess and fistula as complications of inflammatory disease were present in 26 and 14% respectively. In ulcerative colitis, a target sign of the bowel wall was present in 40%, whereas in Crohn's disease a homogeneous wall density was present in all but two cases. Reduced attenuation due to submucosal fat deposits was found in 16% and mucosal tunneling in 27% of cases with ulcerative colitis. Even if severe mucosal destructions were found, the outer contour of the gut was smooth and regular in 95% of the ulcerative colitis cases. CONCLUSION: CT can provide additional information on acuity, extent and complications in inflammatory bowel disease. In combination with conventional radiographic findings a three-step classification for Crohn's disease and ulcerative colitis (early changes, acute and chronic phase) can be proposed.
Adolescent↗
Diagnostic imaging of mesenteric infarction.
PURPOSE: To determine the value of diagnostic imaging in the management of mesenteric infarction. MATERIALS AND METHODS: Within 8 years, 54 patients with mesenteric infarction underwent diagnostic imaging before surgery, including plain radiography (n = 45), ultrasound (US) (n = 29), small bowel follow-through examination (n = 7), colon enema study (n = 7), angiography (n = 16), and computed tomography (CT) (n = 22). Clinical course, laboratory values, and imaging findings were considered in diagnosis. RESULTS: Radiography and US allowed correct diagnoses in five of 18 cases (28%). Only one of 14 fluoroscopic examinations contributed to diagnosis. Fourteen of 16 angiography studies (sensitivity, 87.5%) and 18 of 22 CT examinations (82%) were correct. The difference in sensitivity between CT and angiography was not significant (P > .05). CONCLUSION: CT and angiography are highly sensitive, but CT can also be used to rule out other causes of acute abdomen. Careful evaluation of patient history and clinical situation should lead to suspicion of mesenteric ischemia and early indication for CT.
Aged↗
Image- and model-based surgical planning in otolaryngology.
Preoperative evaluation of any operating field is essential for the preparation of surgical procedures. The relationship between pathology and adjacent structures, and anatomically dangerous sites need to be analyzed for the determination of intraoperative action. For the simulation of surgery using three-dimensional imaging or individually manufactured plastic patient models, the authors have worked out different procedures. A total of 481 surgical interventions in the maxillofacial region, paranasal sinuses, orbit, and the anterior and middle skull base, in addition to neurotologic procedures were presurgically simulated using three-dimensional imaging and image manipulation. An intraoperative simulation device, part of the Aachen Computer-Assisted Surgery System, had been applied in 407 of these cases. In seven patients, stereolithography was used to create plastic patient models for the preparation of reconstructive surgery and prostheses fabrication. The disadvantages of this process include time and cost; however, the advantages included (1) a better understanding of the anatomic relationships, (2) the feasibility of presurgical simulation of the prevailing procedure, (3) an improved intraoperative localization accuracy, (4) prostheses fabrication in reconstructive procedures with an approach to more accuracy, (5) permanent recordings for future requirements or reconstructions, and (6) improved residency education.
Child↗
Three-dimensional spiral CT for neurosurgical planning.
We carried out 22 examinations to determine the value of three-dimensional (3D) volumetric CT (spiral CT) for planning neurosurgical procedures. All examinations were carried out on a of the first generation spiral CT. A tube model was used to investigate the influence of different parameter settings. Bolus injection of nonionic contrast medium was used when vessels or strongly enhancing tumours were to be delineated. 3D reconstructions were carried out using the integrated 3D software of the scanner. We found a table feed of 3 mm/s with a slice thickness of 2 mm and an increment of 1 mm to be suitable for most purposes. For larger regions of interest a table feed of 5 mm was the maximum which could be used without blurring of the 3D images. Particular advantages of 3D reconstructed spiral scanning were seen in the planning of approaches to the lower clivus, acquired or congenital bony abnormalities and when the relationship between vessels, tumour and bone was important.
Adult↗
Ultrasound-guided craniotomy for minimally invasive exposure of cerebral convexity lesions.
The authors describe a method of real-time ultrasound-guided craniotomy for an approach to cerebral convexity lesions. During surgery, a specially designed high frequency (7.5 MHz) sector probe with a thin (11 mm), extended tip is used to image the cerebral lesion through a single burr-hole. The distance between burr-hole and lesion and the direction of the target are then determined from the ultrasound images, and craniotomy is completed with the aid of these parameters. Errors in the preoperative planning of the approach, which might result in incorrect placement of the craniotomy, can easily be recognized and corrected at an early stage of the operation, before the craniotomy has been completed. This technique greatly improves the accuracy in placing craniotomy flaps. Since the risk of misplacing the craniotomy is virtually eliminated in lesions which are identifiable on ultrasound images, the technique allows the surgeon to keep the skull opening as limited as possible.
Brain Neoplasms↗
[Effect of ambient lighting on the diagnostic efficiency of display screen workplaces].
The aim of our study was to determine the influence of ambient lighting conditions on the diagnostic performance when using digital reporting work-stations. We acquired 15 normal and 30 fractured porcine femurs using a storage phosphor system. All images were demonstrated on a high-quality image display under optimised (128 lx) and non-optimised (450 lx) ambient lighting conditions and on a conventional viewing-box under non-optimised conditions (450 lx). Results were analysed using ROC-statistics. The area under the ROC-curve was 0.895 for optimised conditions and 0.684 for non-optimised conditions using digital displays and 0.849 for the conventional viewing-box. The difference in diagnostic performance between optimised and non-optimised conditions using a digital display was highly significant (p < 0.001). Our results emphasise the importance of adequate surrounding lighting conditions for radiologic diagnostic performance, particularly for the use of digital reporting consoles.
Animals↗
Intra-urethral ultrasound in women with stress incontinence.
OBJECTIVE: To investigate whether the sphincter area in women can be seen and quantified with intra-urethral ultrasound (IUUS). Currently, sphincter capacity in women is determined by clinical tests, vaginal palpation, urodynamics and urethral pressure profile. PATIENTS AND METHODS: A pilot study using IUUS was carried out in 32 stress incontinent and 12 healthy women to enable the urethra and para-urethral tissue to be visualized. Round-tipped miniature transducer-containing (20 MHz) catheters (6 and 9 F) were tested. Both provided 15 frames per second. Real-time 360 degrees cross-sectional ultrasound images were obtained by using a standard intraluminal ultrasound system. The external urethral sphincter was visualized and its circumference and area were measured. RESULTS: IUUS provided high resolution imaging of the urethra and surrounding tissues. The whole length of the urethra was visualized. The external sphincter was easily recognized as an oval-shaped, hypoechoic structure. Examination of 44 stress incontinent and healthy women revealed a negative correlation between the external urethral sphincter (area and circumference) and the grade of stress incontinence (P < 0.01). In no patient with normal urinary continence was the sphincter reduced in size (< 2.8 cm circumference). CONCLUSION: IUUS is a useful technique in the diagnosis of incontinence, as conventional methods provide little information on the sphincter itself. The evaluation of sphincter size and morphology could help in the choice of therapy.
Female↗
[High-resolution CT of the dentate alveolar ridge in comparison with histological thin section preparations].
Human bone segments of the toothed jaw were scanned using high-resolution CT with axial and coronal contiguous 1 and 2 mm slices. The bone segments were sliced analogous to the performed CT image positions. Contact films and micro-sections were made from the cuttings. Length and width of the teeth, the thickness of the alveolar bone and the distance between bone and dental surface were measured. Comparison of the CT measurements with contact films and histological specimen yielded best results for axial slices with 1 mm slice thickness (mean error 0.3-0.5 mm). Coronary oriented slices showed an error of 0.3-1.6 mm. 3D-reformatting can improve spatial orientation for axially produced image series. For CT imaging of the toothed jaw concerning the dento-alveolar structures, contiguous axial scanning with 1 mm slice thickness appears to be the concept of choice.
Alveolar Process↗
[The diagnosis of focal liver lesions by the texture analysis of dynamic computed tomograms].
Characterisation of focal liver lesions on computed tomography (CT) depends on correct interpretation of morphology and dynamic changes during bolus injection of contrast medium. The aim of this study was to develop a texture analysis concept for computer based interpretation of dynamic CT images. 148 focal liver lesions were investigated by serial CT. The study comprised 61 haemangiomas, 25 other benign lesions (FNH/adenomas) and 62 malignant lesions (primary or secondary). FNH, adenomas and malignant lesions were histologically proven. Diameter was 8-145 mm (mean 31 mm). Regions of interest were interactively defined. After extraction of characteristic textural features, a pattern classifier was trained. All CT series were evaluated using the "leaving-one-out" method. 134 of the 148 lesions were correctly classified (positive predictive value 0.9). Sensitivity for the presence of malignancy was 0.93 (80/86), specificity was 0.9 (56/62). False classification of a lesion was found to depend strongly on the quality of the examination (bolus intensity, positional change of the lesion due to respiratory movements).
Diagnosis, Differential↗
Digital radiography versus conventional radiography for the detection of a skull fracture under varying exposure parameters.
RATIONALE AND OBJECTIVES: The effect of varying exposure parameters on the detectability of a fracture with digital and conventional radiography were examined. METHODS: A macerated fractured skull was imaged by film-screen radiography (FSR) and digital storage phosphor radiography (DR) with various exposure values. Five radiologists traced the course of a fracture line. The length of the fracture was reported and the results were analyzed by Student's t test for paired samples. RESULTS: At 35% of the conventional radiation dose, the standard DR screen displayed an average of 48% of the fracture length. The difference from the conventional image (45%) was not significant in this case. An increase of the dose to ten times the conventional dose (250 mAs) yielded no significant improvement in the detectability of the length of the fracture (51%). CONCLUSIONS: This experiment shows that with use of the DR with the standard screen, a dose reduction of approximately 35% appears to be possible without any resulting loss of image quality compared to FSR. Use of the high resolution screens should be avoided, since they require a higher incident image dose than standard screens without offering any diagnostic advantages. The image dose of digital radiographs can be roughly estimated based on the digital device sensitivity value. As a rule, the sensitivity value should range between 100 and 200.
In Vitro Techniques↗
Double contrast small bowel follow-through with an acid-resistant effervescent agent.
RATIONALE AND OBJECTIVES: A new technique was developed to achieve double contrast examinations in the small bowel without intubation. METHODS: Effervescent granules and tablets were coated with an acid-resistant acrylic lacquer to provide selective enteric gas release. The coating thickness was 15% of dry weight for the granules and 1 to 4.5 mg/cm2 for the tablets. Fifty patients were examined using the method in a controlled study. All examinations were reviewed by two radiologists using a three-step quality score. The results were compared to 20 enteroclysis examinations. RESULTS: Image quality was better for the coated tablets compared with the granules (P < .01). The double-contrast small bowel follow-through (DC-SBFT) provided a better quality examination in the terminal small bowel than in the jejunum. Enteroclysis yielded better results for the jejunum, but was not superior in the terminal ileum. Average time of fluoroscopy was 477 seconds for the DC-SBFT (n = 50) compared with 952 seconds for patients receiving enteroclysis (n = 528). No side effects or adverse reactions occurred due to contrast media application. CONCLUSIONS: The results of this new method are preliminary, yet promising. For young patients and certain indications it may provide a less invasive alternative to enteroclysis.
Abdominal Pain↗
Comparative evaluation of digital radiography versus conventional radiography of fractured skulls.
OBJECTIVES: The authors assessed the relative efficacy of conventional and digital storage-phosphor radiographs for the detection of skull fractures. METHODS: Fifty conventional film-screen radiographs (FSR) and 50 digital storage-phosphor radiographs (DR) with 66 fractures were compared. Five radiologists evaluated image quality and fracture detectability. The results were analyzed by receiver operating characteristic (ROC) curve analysis. RESULTS: With a standard exposure, the ability to evaluate skull fractures was equally good with either technique (ROC area for DR, 0.8954; for FSR, 0.8870). Digital radiography was superior in evaluating nasal bone. For petrosal bone, the DR image simulates an underexposure. This disadvantage compared with FSR can be compensated by image postprocessing. CONCLUSION: In evaluation of skull fractures, radiologists performance with DR is equivalent to FSR.
Adolescent↗
Assessment of incontinence with intraurethral US: preliminary results.
To explore the usefulness of intraluminal ultrasound (US) for diagnostic imaging of the female urethra, 22 female patients with different degrees of urinary incontinence and 10 female patients with normal continence underwent examination by means of a 20-MHz intravascular US system. Contiguous sections were used for three-dimensional reconstructions on a personal computer-based system in two patients. The circumference and area of the internal urethral sphincter were measured in all patients; the measurements were obtained by means of manual delineation of the inner and outer contours of the sphincter. A correlation was found between (a) area and circumference and (b) the degree of incontinence (P < .01). No patient with normal urinary continence showed a reduced sphincter size (a circumference smaller than 2.8 cm). Intraurethral US, which yields images of the urethra and surrounding tissues, may become an important adjunct to urethrography and functional methods (assessment of urodynamics) for the diagnostic evaluation of incontinence.
Female↗
Computed tomographic cholangiography using spiral scanning and 3D image processing.
Volumetric computed tomography (CT) scans ("spiral CT") were performed after intravenous (i.v.) cholangiography followed by additional 3D surface reconstructions of gallbladder and biliary ducts. 34 patients were investigated prior to cholecystectomy. No allergic adverse reactions were observed. The scan time was 24 s. Contrast enhancement in the extrahepatic bile duct and gallbladder were measured. All CT image series were reviewed independently by four experienced physicians (two radiologists, two surgeons) and compared for quality with conventional cholangiography on a three-point scale. The average rating for the demonstration of the biliary tract was significantly better for spiral CT than for conventional cholangiography (p < 0.01). In all cases sufficient contrast was found in the common bile duct (mean 315 HU). 3D imaging was considered to be helpful for intraoperative orientation during laparoscopic surgery.
Adult↗
Stereolithographic modelling for reconstructive head surgery.
Until now, bounds of model creation of medical objects had to be set because of the limited capabilities of available manufacturing equipment. Recently, stereolithography was developed as an alternative to current milling operations. In this process the surface of a photohardening liquid plastic compound is traced by a laser beam and hardened in layers. The models thus produced are extremely accurate and retain excellent detail. Specific implants can be designed and prepared as is illustrated in a case report. If tissue-compatible plastics are used, custom-made implants could soon be manufactured directly with the technique described.
Child↗
[Computed tomographic imaging of the dentoalveolar-maxillary sinus lacuna of the dentate jaw].
A human bone segment of the lateral maxilla was scanned using high-resolution computed tomography (CT) in contiguous parallel axis slices in order to image the topographical relationship between upper molars and the maxillary sinus. The bone segment was dissected analogously in 1 mm thick sections. After exposing contact films from these jaw cuttings, microsections were made for histological interpretation. The radiological-histological comparison between the CT-scans, contact films and the histologic specimens revealed absolute differences of 0.2-0.6 mm. The high resolution CT allowed an interpretation of details located between teeth and bone when the minimum bone thickness was 0.5 mm or more. First experiences with the CT-technique in orthodontic patients were promising, especially for the differential diagnosis of the dentoalveolar maxillary sinus relation.
Adult↗