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C Rock

Publications and source records attributed to C Rock.

At least 19 recordsLinked to original sources
PubMed2003

[Computed tomography in the diagnosis of inflammatory bowel disease -- methodology of MSCT and clinical results].

PURPOSE: This paper discusses the diagnostic yield of multislice computed tomography (MSCT) in inflammatory bowel disease. METHODS: Contrast media are administered intraluminally (colon, small intestine) and intravenously (triple contrast CT). Filling of small bowel is achieved by means of jejunal tube ("Sellink CT") or via the oral route. Pharmacological relaxation of the intestine decreases motion artifact. Intraluminal contrast media consist of either hyperdense, "positive" or hypodense, "negative" liquids. RESULTS: Thin-slice MSCT of the entire abdomen allows high-quality post processing (MPR, thin-slice MIP). Due to superior distension, Sellink CT improves estimation of stenosis or changes in thickness and contrast of bowel wall. Positive contrast is superior in the detection and preoperative localization of abscess, fistula or conglomerate tumour, because it accurately differentiates between intra- and extraluminal structures.However, negative contrast facilitates quantitative evaluation of bowel wall thickening or enhancement and demonstrates gastrointestinal bleeding. CONCLUSION: MSCT of the small intestine is superior to conventional enteroclysis, especially in the diagnosis of mesenterial or other extraintestinal disease. As a side effect, the colon is assessed in the same examination. Radiation dose is less in MSCT (7.8-13.3 mSv) than in conventional fluoroscopy (13.99+/-7.57 mSv). MSCT can be performed as an alternative or adjunct to colonoscopy, if endoscopic access is restricted. It is already the imaging modality of choice in acute diverticulitis.

Administration, Oral↗
PubMed2003

[Radiological interventions in inflammatory bowel disease].

INTRODUCTION: Abscesses, fistulas,hemorrhages and stenoses are common complications of inflammatory bowel diseases. This study provides an overview on various methods of radiological intervention and the clinical usefulness of these methods is analyzed. METHODS: The success rate of percutaneous abscess drainage (PAD), embolisation of hemorrhages and dilatation of bowel stenoses is reviewed and current literature is addressed. Success rate is defined in terms of cure rate and need for subsequent surgery. RESULTS: After PAD, surgery can be avoided during the observation period in about 50% of patients with abscesses due to Crohn's disease and diverticulitis. Preoperative PAD reduces the degree of invasiveness and thus the risk of surgery. Abscess recurrence is found with the same frequency following surgery or PAD. Bowel dilatation can be performed both with radiological and with endoscopic guidance.Embolisation of GI-hemorrhage is technically feasible, but the indication should be limited to strictly selected cases. CONCLUSIONS: In treating abscesses and fistulas associated with Crohn's disease and diverticulitis, PAD is a valuable treatment option. Embolisation or dilatation are restricted to rare cares.

Abdominal Abscess↗
PubMed2002

[The value of magnetic resonance cholangiography for the expedient diagnosis of choledocholithiasis].

INTRODUCTION: Management of symptomatic cholecystolithiasis is vitally influenced by dilated biliary tract and choledocholithiasis. The objectives of this prospective pilot study were to evaluate the diagnostic value of preoperative magnetic resonance cholangiography (MRC) compared to diagnostic endoscopic retrograde cholangiography (ERC) and to establish an efficient algorithm for diagnostics and treatment of choledocholithiasis. METHODS: All consecutive patients with cholecystolithiasis and dilated biliary tract proven by sonography as well as elevated liver function tests were enrolled within 12 months. Patients without evidence of bile duct calculi underwent preoperative MRC, whereas patients with choledocholithiasis immediate ERC. RESULTS: 58 patients (30 male, 28 female) with a median age of 59.4 years underwent preoperative MRC. In 18 patients (10 male, 8 female; median age 63.5 years) with evidence of choledocholithiasis we subsequently performed ERC and papillotomy. Bile duct stones were detected and removed after papillotomy in 10 patients, whereas calculi could not be found anymore in 8 patients. The remaining 40 patients without calculi evident on MRC were transferred to magnetic resonance tomography and ERC in case of suspected malignancy or to cholecystectomy and intraoperative cholangiography (IOC), which could definitely exclude choledocholithiasis. In comparison to ERC respectively IOC, MRC was able to detect bile duct stones with a sensitivity of 100% and a specificity of 83.3%. CONCLUSIONS: Non-invasive MRC seems to replace diagnostic ERC concerning the presence of choledocholithiasis in case of cholecystolithiasis and dilated biliary tract with a high sensitivity. The preoperative ERC with stone extraction is still the therapy of choice in case of radiologically confirmed choledocholithiasis.

Aged↗
PubMed2002

[Structured radiologic diagnosis in polytrauma].

PURPOSE: Development of a concept for structured diagnostic imaging in patients with multiple trauma. MATERIAL AND METHODS: Evaluation of data from a prospective trial with over 2400 documented patients with multiple trauma. All diagnostic and therapeutic steps, primary and secondary death and the 90 days lethality were documented. Structured diagnostic imaging of multiple injured patients requires the integration of an experienced radiologist in an interdisciplinary trauma team consisting of anesthesia, radiology and trauma surgery. Radiology itself deserves standardized concepts for equipment, personnel and logistics to perform diagnostic imaging for a 24-h-coverage with constant quality. RESULTS: This paper describes criteria for initiation of a shock room or emergency room treatment, strategies for documentation and interdisciplinary algorithms for the early clinical care coordinating diagnostic imaging and therapeutic procedures following standardized guidelines. Diagnostic imaging consists of basic diagnosis, radiological ABC-rule, radiological follow-up and structured organ diagnosis using CT. Radiological trauma scoring allows improved quality control of diagnosis and therapy of multiple injured patients. CONCLUSION: Structured diagnostic imaging of multiple injured patients leads to a standardization of diagnosis and therapy and ensures constant process quality.

Emergency Service, Hospital↗
PubMed2002

[Detection of tibial condylar fractures using 3D imaging with a mobile image amplifier (Siemens ISO-C-3D): Comparison with plain films and spiral CT].

PURPOSE: To analyze a prototype mobile C-arm 3D image amplifier in the detection and classification of experimental tibial condylar fractures with multiplanar reconstructions (MPR). METHOD: Human knee specimens (n = 22) with tibial condylar fractures were examined with a prototype C-arm (ISO-C-3D, Siemens AG), plain films (CR) and spiral CT (CT). The motorized C-arm provides fluoroscopic images during a 190 degrees orbital rotation computing a 119 mm data cube. From these 3D data sets MP reconstructions were obtained. All images were evaluated by four independent readers for the detection and assessment of fracture lines. All fractures were classified according to the Müller AO classification. To confirm the results, the specimens were finally surgically dissected. RESULTS: 97 % of the tibial condylar fractures were easily seen and correctly classified according to the Müller AO classification on MP reconstruction of the ISO-C-3D. There is no significant difference between ISO-C and CT in detection and correct classification of fractures, but ISO-CD-3D is significant by better than CR. CONCLUSION: The evaluation of fractures with the ISO-C is better than with plain films alone and comparable to CT scans. The three-dimensional reconstruction of the ISO-C can provide important information which cannot be obtained from plain films. The ISO-C-3D may be useful in planning operative reconstructions and evaluating surgical results in orthopaedic surgery of the limbs.

Humans↗
PubMed2002

[Studies on image quality, high contrast resolution and dose for the axial skeleton and limbs with a new, dedicated CT system (ISO-C-3 D)].

PURPOSE: Evaluation of 3D-CT imaging of the axial skeleton and different joints of the lower and upper extremities with a new dedicated CT system (ISO-C-3D) based on a mobile isocentric C-arm image amplifier. MATERIAL AND METHODS: 27 cadaveric specimes of different joints of the lower and upper extremities and of the spinal column were examined with 3D-CT imaging (ISO-C-3D). All images were evaluated by 3 radiologists for image quality using a semiquantitative score (score value 1: poor quality; score value 4: excellent quality). In addition, dose measurements and measurements of high contrast resolution were performed in comparison to conventional and low-dose spiral CT using a high contrast phantom (Catphan, Phantom Laboratories). RESULTS: Adequate image quality (mean score values 3 - 4) could be achieved with an applied dose comparable to low-dose CT in smaller joints such as wrist, elbow, ankle and knee. A remarkably inferior image quality resulted in imaging of the hip, lumbar and thoracic spine (mean score values 2 - 3) in spite of almost doubling the dose (dose increased by 85 percent). The image quality of shoulder examinations was insufficient (mean score value 1). Phantom studies showed a high-contrast resolution comparable to helical CT in the xy-axis (9 lp/cm). CONCLUSION: Preliminary results show, that image quality of C-arm-based CT-imaging (ISO-C-3D) seems to be adequate in smaller joints. ISO-C-3D images of the hip and axial skeleton show a decreased image quality, which does not seem to be sufficient for diagnosing subtle fractures.

Arm↗
PubMed2002

[Focal secondary malignant liver lesions: MnDPDP-enhanced MRT at 0.2 tesla vs. helical CT-arterioportography].

PURPOSE: Prospective evaluation of the efficacy of MnDPDP- enhanced MRI using an open low-field scanner for the detection of focal malignant liver lesions in comparison with helical CT- arterioportography (CT AP). MATERIAL AND METHODS: As part of a phase III study, 27 consecutive patients we enrolled for comparison, with seven patients later eliminated for failing the inclusion criteria. Native and MnDPDP-enhanced MRI of the liver at a field-strength of 0.2 Tesla (Siemens Magnetom Open) and DSA with helical CT AP (Siemens Somatom Plus 4) were performed within one week. The lesions were compared collectively and after categorization by size: (a) < 1 cm, (b) 1 - 2 cm, and (c) > 2 cm. For statistical evaluation, the sign test with a significance level of p < 0.05 was used. RESULTS: CT AP depicted 114 lesions, whereas native MRI detected 62 and MnDPDP-enhanced MRI revealed 69 lesions. Significant differences were shown for collective comparison and for selective comparison of category (b), and of categories (a) and (b) combined. No significant differences were found between native and contrast-enhanced MRI. CONCLUSION: MnDPDP should be reserved for high-field strengths since low field strengths cannot be expected to confirm or exclude malignant liver lesions reliably.

Adult↗
PubMed2001

[Introduction of a new mobile C-arm/CT combination equipment (ISO-C-3D). Initial results of 3-D sectional imaging].

Preclinical evaluation of a new mobile C-arm image amplifier with an option for three-dimensional computed tomography (CT) imaging (prototype Iso-C3D) with respect to high-contrast resolution and possible clinical applications. Cadaveric specimens (n = 30) of different joints of the lower and upper extremities and specimens of the spinal column were examined with the Iso-C3D and evaluated for image quality. In addition, using a high-contrast phantom (Catphan, Phantom Laboratory, Salem, N.Y., USA) and a fracture model of the femoral bone, measurements of high-contrast resolution were performed in comparison to spiral CT. With the exception of the shoulder, all joint regions including the entire spinal column could be examined. Adequate image quality could be achieved in smaller joints such as the wrist, elbow, ankle, and knee, whereas a remarkably decreased image quality was found when imaging the hip as well as the lumbar and thoracic spine. Images of the phantom study and high-contrast fracture model showed a high-contrast resolution comparable to helical CT (9 Lp/cm in xy-axis). In smaller joints, the image quality of the mobile C-arm CT imaging system (Iso-C3D) is comparable to that of helical CT. Image quality in examinations of the hip and lumbar and thoracic spine seems to be sufficient for intraoperative control studies of osteosynthesis. Problems still occur in shoulder examinations.

Arthrography↗
PubMed2001

[3-D imaging with a mobile surgical image enhancement equipment (ISO-C-3D). Initial examples of fracture diagnosis of peripheral joints in comparison with spiral CT and conventional radiography].

To analyze a prototype mobile C-arm image amplifier (Iso-C3D) in the evaluation of different joint fractures of the upper and lower limbs using multiplanar reconstruction (MPR). Different cadaver joint specimens (n = 14) were examined with a prototype (Iso-C3D, Siemens AG, Erlangen, Germany), plain radiographs (CR), and spiral computed tomography (CT). The motorized C-arm provides fluoroscopic images during a 190 degrees orbital rotation computing a 119-mm data cube. These three-dimensional data sets yielded MPR images, which were evaluated by two readers for the detection and extent of fracture lines. Initial data show that fractures were easily depicted and correctly classified on MPR images with the Iso-C3D and that there was no difference between the Iso-C and CT in the detection of fractures. The preliminary results suggest a remarkably good detection of joint fractures with the Iso-C3D. Studies in an adequate number of patients are required to elucidate whether these promising results can also be obtained in a clinical setting.

Ankle Injuries↗
PubMed1999

[Temporary balloon occlusion as therapy of uncontrollable arterial hemorrhage in multiple trauma patients].

PURPOSE: Presentation of temporary balloon occlusion as an interventional radiological method for managing hemorrhage in multiply injured patients with uncontrollable loss of blood. METHOD: Temporary, non-selective arterial occlusion by introduction of a balloon catheter contralaterally to the source of bleeding has been performed since 1992 on 7 patients with multiple injuries, hemorrhagic shock requiring reanimation, and angiographic demonstration of an arterial hemorrhage in the supply region of the internal iliac artery with complex pelvic fracture. In each case a PTA balloon catheter was introduced transfemorally, non-selectively positioned proximal to the bleeding source, and left in place for 24-48 h under manometric control. Control angiographies were performed prior to catheter removal. RESULTS: The bleeding was stopped immediately in all 7 patients. The hemodynamic stability made transport and thus further surgical management and/or a short-term treatment in the intensive-care station possible. Control angiographies confirmed that the bleeding had stopped in all patients. CONCLUSIONS: We recommend temporary balloon occlusion as a rapid and effective method for the management of bleeding in otherwise uncontrollable traumatic hemorrhages in the supply region of the internal iliac artery.

Adult↗
PubMed1999

Noninvasive diagnosis of emphysema. Aerosol morphometry and aerosol bolus dispersion in comparison to HRCT.

Aerosol-derived airway morphometry (ADAM) and aerosol bolus dispersion (ABD) test are altered in patients with emphysema. We examined the diagnostic power of these aerosol methods in comparison with the noninvasive "gold-standard" HRCT in 50 consecutive patients with various lung diseases. The severity of airflow limitation was mild to moderate in the group of patients without emphysema and moderate to severe in the group of patients with HRCT-confirmed emphysema (FEV(1), 78 +/- 23% pred versus 53 +/- 33% pred; p < 0. 001). Among all lung function parameters under consideration ADAM showed the highest sensitivity and specificity for separating patients with emphysema from those without emphysema (area under the operating characteristics curve: p(ROC), 0.92), followed by ABD (p(ROC), 0.90), a marker for ventilation inhomogeneities. In patients with HRCT-confirmed macroscopic emphysema, peripheral air-space dimensions (EAD) at a relative volumetric lung depth V(pr) of 0.20 measured by ADAM were 155% larger, and bolus dispersion (ABD) at a lung depth of V(p) 600 ml was 53% larger than those observed in patients with other lung diseases (EAD = 0.84 +/- 0.53 mm versus 0.33 +/- 0.10 mm, p < 0.0001; ABD = 706 +/- 154 cm(3) versus 462 +/- 109 cm(3); p < 0.0001). EAD showed a significant correlation with the HRCT visual score (r = 0.78, p = 0.01). ABD showed weak significant correlations with all HRCT parameters under consideration (visual score, pixel density, mean lung density) (r = 0.45 to 0.66; p < 0.05). ADAM and ABD are powerful tools for the noninvasive diagnosis of macroscopic emphysema.

Aerosols↗
PubMed1998

[Dosimetry in conventional and spiral CT in 8 spiral CT scanners of the latest generation].

PURPOSE: Measurement of scanner-dependent differences in PCTDI for conventional and spiral CT and evaluation of PCTDI/100 mAs in eight spiral CT scanners of the latest generation. METHODS: Central PCTDI was evaluated in a PMMA phantom for different scan lengths of conventional and spiral CT in four scanners. Central and peripheral PCTDI/100 mAs, average dose and the quotient between peripheral and central PCTDI/100 mAs were measured with a dedicated 10 cm ionisation chamber positioned within a PMMA phantom using the parameters of a standardised liver protocol and a high-resolution inner ear protocol for eight spiral CT scanners. RESULTS: Depending on scanner type and scan length PCTDI for the spiral mode is in a range between 11.3% higher and 4.3% lower than that for the conventional mode. PCTDI/100 mAs varies considerably between different CT scanners. For the standardised liver protocol PCTDI/100 mAs varies up to a factor of 2, for the inner ear protocol up to a factor of 4. CONCLUSION: Even in comparable modern CT scanners there are considerable protocol and scanner-dependent differences in PCTDI/100 mAs. The values for his own scanner should be known to each CT user so that he can develop a dose-optimised, patient and problem-orientated examination strategy.

Ear, Inner↗
PubMed1998

Radiation dose and image quality in spiral computed tomography: multicentre evaluation at six institutions.

The purpose of this study was to evaluate the correlation of radiation dose with image quality in spiral CT. Seven clinical protocols were measured in six different radiological departments provided with four different types of high specification spiral CT scanners. Central and surface absorbed doses were measured in acrylic. The practical CT dose index (PCTDI) was calculated for seven clinical examination protocols and one standardized protocol using identical parameters on four different spiral CT scanners with a dedicated ionization chamber inserted into PMMA phantoms. For low contrast measurements, a cylindrical three-dimensional (3D) phantom (different sized spheres of defined contrast) was used. Image noise was measured with a cylindrical water phantom and high contrast resolution with a Perspex hole phantom. Image quality phantoms were scanned using the parameters of the clinical protocols. Images were randomized, blinded and read by six radiologists (one from each institution). PCTDI values for four different scanners varied up to a factor between 1.5 (centre) and 2.2 (surface) for the standardized protocol. A greater degree of variation was observed for seven clinical examination protocols of the six radiological departments. For example, PCTDI varied up to a factor between 1.7 (cerebrum protocol) and 8.3 (abdomen paediatric protocol). Low contrast resolution correlates closely with dose. An improvement in detection from 8 mm to 4 mm sized spheres needs approximately a ten-fold increase in dose. Noise shows a moderate correlation with PCTDI. High contrast resolution of clinical protocols is independent of PCTDI within a certain range. Differences in modern CT scanner technology seem to be of less importance for radiation exposure than selection of protocol parameters in different radiological institutes. Future discussion on guidelines regarding optimal (patient adapted) tube current for clinical protocols is desirable.

Brain↗
PubMed1998

[Stress on the wrist joint in semilunar bone necrosis--a morphologic study in vivo].

The distribution of subchondral mineralization of the distal articular surface of the radius was examined by CT osteoabsorptiometry in both wrists of twelve patients showing different stages of Kienböck's disease. The pattern of density distribution had already been demonstrated in previous studies to be an adequate parameter for assessing axial loading across the wrist joint in the patients. Contrary to the anticipated presence of predominant stress in the lunate compartment, some patients showed identical stress in the compartment of the scaphoid, and the balanced loading of both compartments, as before. Even when in early stages of the disease the lunate type of mineralization appeared more often, it was still not possible to demonstrate general excessive stress on the lunate. We have therefore concluded that the main stress in the scaphoid compartment might be a secondary effect, which is to be regarded as the expression of the advancing destruction of the lunate and consequent loss of load transmission through this compartment. This hypothesis is also supported by the fact that, in progressive stages of Kienböck's disease, the density maximum in the fovea lunata, generally present in healthy people, is absent. Furthermore, in patients with necrosis of the lunate, the total mineralization in terms of the maximal density values in the distal joint surface of the radius is in the majority of cases less than in the normal subject. In two cases, even the density maximum was absent from the fovea lunata of the contralateral wrist joint, without there being any clinical signs suggesting a possible lunate necrosis on this side. We interpret these pathological changes in the unaffected wrist joint as a further indication that we are dealing with a congenital predisposition which affects both wrist joints.

Absorptiometry, Photon↗
PubMed1997

Direct comparison of contact areas, contact stress and subchondral mineralization in human hip joint specimens.

X-ray densitometric and CT osteoabsorptiometric findings suggest that in the human hip subchondral mineralization patterns change from bicentric to monocentric as a function of age. It has been hypothesized that these changes indicate an alteration in the geometric configuration of the joint from incongruous to congruous, possibly associated with the onset of osteoarthrosis. The purpose of this study was therefore to directly compare contact rates, contact stress and subchondral mineralization in the hip joint. Twelve specimens without cartilage lesions (ages 34-86 years) were investigated. Simulating the mid-stance phase, the contact areas were determined by polyether casting and the contact stress with Fuji film. The distribution of subchondral mineralization was assessed non-invasively with CT osteoabsorptiometry. At small loads the load-bearing areas were located at the periphery of the lunate surface. In some joints they were found in the acetabular roof and expanded, with higher loads, to the center of the lunate surface and the anterior and posterior horns. In other joints, the contact areas were recorded at lower loads in the anterior and posterior horns, and only at higher forces they merged in the acetabular roof. The maximal contact stress ranged from 8 t 9 MPa at 300% body weight. Maxima of subchondral mineralization were recorded in the acetabular roof, in the anterior and posterior horns, or in all three locations. There was no clear correlation between the distribution of contact and pressure, and the pattern of subchondral bone density. Incongruity is shown to strongly affect the distribution of contact and pressure in the human hip joint. However, the pattern of subchondral mineralization cannot be readily explained in terms of the contact areas and contact stress during mid-stance. Incongruity may give rise to tensile stresses in the subchondral bone, and the construction of the pelvis as a whole may play an important role in subchondral bone loss loads and adaptation.

Adult↗
PubMed1997

Altered patterns of subchondral bone mineralization in Kienböck's disease.

The pattern of subchondral bone density, which is supposed to reflect the long-term distribution of stress, was investigated in both wrist joints of nine healthy young subjects and seven patients suffering from Kienböck's disease by means of CT osteoabsorptiometry. Two density maxima were found on the distal articular surface of the radius in the healthy subjects, corresponding to the position of the scaphoid and the lunate. Our relative quantitative results showed three different physiological types of stress indicated by the predominantly monocentric density maxima either on the scaphoid or the lunate surface of the radius and the symmetrical distribution of the mineralization. In Kienböck's disease no type of mineralization predominated. In the progressive stages the lunate density maximum was absent. The overall mineralization was generally less than in controls. Changes in the pattern of mineralization were also found on the contralateral side.

Adult↗