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Biomedical subjects

J F Schäfer

Publications and source records attributed to J F Schäfer.

8 recordsLinked to original sources
PubMed2005

Prevalence of vertebral alterations and the effects of calcium and vitamin D supplementation on calcium metabolism and bone mineral density after gastrectomy.

BACKGROUND: Bone disease is common after gastrectomy, resulting in decreased bone mass and an increased risk of fracture. No proven therapy is currently available. METHODS: Serum markers of calcium metabolism in 98 patients after partial or total gastrectomy were compared with those in 30 age- and sex-matched healthy controls. Patients with disorders of calcium metabolism were investigated by conventional radiography and single-energy computed tomography of the spine. Forty patients participated in a 1-year follow-up study to investigate the effects of vitamin D and calcium supplementation on calcium metabolism and bone mineral density. RESULTS: Altered serum markers of calcium and phosphate metabolism were observed in 77 (79 per cent) of 98 patients. Sixty (79 per cent) of these had vertebral alterations. Vertebral fractures were detected in 22 patients, grade I vertebral deformities in 50 patients, grade II deformities in 22 patients and osteopenia (Z-score less than - 1) in 30 patients. Calcium and vitamin D supplementation resulted in an increase in 25-hydroxy-vitamin D (P < 0.001), 1,25-dihydroxy-vitamin D (P = 0.048) and osteocalcin (P = 0.045), whereas levels of parathyroid hormone were decreased (P = 0.007). Bone mineral density did not change over time. CONCLUSION: Disturbances of calcium and bone metabolism are common after gastrectomy. Calcium and vitamin D supplementation normalized levels of markers of calcium metabolism and might have prevented age-related bone mass loss, although it did not increase bone mineral density after 1 year.

Biomarkers↗
PubMed2005

[Detection of pulmonary nodules with breath-hold magnetic resonance imaging in comparison with computed tomography].

PURPOSE: Evaluation of sensitivity and false positive findings of two fast MRI sequences for the detection of pulmonary nodules in comparison with spiral CT by two independent observers. MATERIALS AND METHODS: All 30 enrolled patients had a spiral CT or MSCT as base line study. MRI was performed with a 1.5 T MR scanner (Sonata, Siemens) using a transverse 3D gradient echo sequence (3D-GRE: TR/TE/flip = 2.9 ms/1.1 ms/5 degrees ) and a half-Fourier single-shot fast spin-echo sequence (HASTE: TR/TE/flip = 800/25/150 degrees ) acquired in three planes. A separate analysis for both sequences was carried out prospectively by two independent readers (A and B) with different experience regarding pulmonary MRI. Additionally, a retrospective reading with knowledge of the CT scans was done. Results were calculated for all lesions and for lesions larger than 4 mm. RESULTS: The sensitivities were 73 %, 70 % and 84 % for the 3D-GRE sequence (reader A, reader B, retrospective reading) and 65 %, 68 % and 81 % for the HASTE sequence. For lesions larger than 4 mm, the sensitivities were 93 %, 89 %, 96 % for the 3D-GRE sequence and 85 %, 85 %, 96 % for the HASTE sequence. The rate of false positive findings depended on the reader's experience, but was generally lower for the 3D-GRE sequence with 2 and 16 (reader A and B) false positive nodules compared to 4 and 40 false positive findings for the HASTE sequence. The 3D-GRE sequence was more accurate for both readers (reader A: p = 0.08, reader B: p = 0.00003). CONCLUSION: The sensitivity of MRI for the detection of lung nodules was only acceptable for lesions larger than 4 mm. The 3D-GRE sequence is superior to the HASTE sequence due to the reduced amount of false positive findings with comparable sensitivity.

Adult↗
PubMed2004

[Oncologic screening with whole-body MRI: possibilities and limitations].

In the last decade the interest in radiological screening examination increased among informed laymen enormously. Independent from the evidence of whole-body examinations for cancer prevention the discussion about screening must again be considered again due to the newest technical developments, since MRI of the whole-body with high spatial resolution is feasible now within one single examination. The newest system permits simultaneous connection of up to 76 coil elements and signal reception from 32 independent receiving channels. Whole-body MRI including magnetic resonance colonography (MRC) is feasible within 60 min. In this review potential investigation protocols will be presented. Potentials, challenges and limitations of whole-body MRI in the prevention of the malignancies most frequently leading to death are discussed on the basis own experiences examples and the literature.

Aged↗
PubMed2002

[CT-colonography: current status and future directions in consideration of the technical evolution].

Computertomography and with it CT-colonography evolves technically and also possibilities of data processing proceed rapidly. The current status of CTC can be summarized as follows:The method represents a true alternative to barium enema if technical conditions are given.CTC can be performed with excellent results immediately following an incomplete colonoscopy. In pretherapeutic diagnosis of colorectal carcinoma, CTC can be combined with a staging CT of the abdomen. The recent technical advances with new 16 row technology in image quality and data acquisition - mainly concerning the spatial and temporal resolution - are very promising. Developments in postprocessing of CT data can also contribute to a higher efficiency of labor. Alternative preparation schemata can lead to a more comfortable bowel cleansing and stool labeling can even avoid this procedure, resulting both in an even improved compliance. Radiation exposure in low dose technique is comparable to a double contrast barium enema and can be still reduced by optimisation of scanning parameters.The aim of the following article is (1 to give an overview of the current status of patient preparation, image acquisition and data processing; (2) to review recent clinical trials and experimental studies and to show future directions of CTC with regard to the clinical development.

Colonic Polyps↗
PubMed2002

[Imaging diagnosis of solitary pulmonary nodules on an open low-field MRI system--comparison of two MR sequences with spiral CT].

OBJECTIVE: To evaluate and compare two fast gradient-echo sequences (GRE) concerning the visualization of solitary pulmonary nodules with an open low-field MRI system in comparison to computed tomography. MATERIALS AND METHODS: Fourteen patients with solitary pulmonary nodules detected by spiral CT ranging in size from 6 mm to 42 mm (mean 20 mm) underwent MRI on an open 0.2 T scanner using a spoiled 2D GRE (2D FLASH; TR/ TE/Flip = 100 ms/7.5 ms/30 degrees ) and a totally refocused 2D steady-state GRE (True-FISP; TR/TE/FA = 7.3 ms/3.5 ms/80 degrees ). The image quality concerning artifacts (by flow, breathing and susceptibility) and the morphologic characteristics of the nodules were scored and compared with CT by two independent radiologists. The diameters of the nodules measured by MRI were compared with CT measurements. The sequences were also evaluated with regard to the signal-to-noise ratio (SNR) of the lesion. RESULTS: All lesions were detected with the 2D FLASH sequence. True-FISP failed to find a granuloma with a size of 6 mm. The 2D FLASH was rated significantly superior to true FISP concerning image quality artifacts by susceptibility as well as concerning to CT the presentation of nodule characteristics. In MR images, the size of lesions was significantly smaller than in CT images for both sequences: for 2D FLASH the mean difference was 0.9 mm and for true FISP 2.6 mm. The SNR of the nodules was significantly higher for the 2D FLASH than for the true FISP. CONCLUSION: In low field MRI, the 2D FLASH sequence is superior to the 2D true FISP sequence in imaging of pulmonary nodules. With the 2D FLASH sequence nodules of 6 mm or larger in size can be visualized.

Aged↗
PubMed2001

[Hybrid 3-D rendering of the thorax and surface-based virtual bronchoscopy in surgical and interventional therapy control].

PURPOSE: The aim of this study was to demonstrate the possibilities of a hybrid rendering method, the combination of a color-coded surface and volume rendering method, with the feasibility of performing surface-based virtual endoscopy with different representation models in the operative and interventional therapy control of the chest. MATERIAL AND METHOD: In 6 consecutive patients with partial lung resection (n = 2) and lung transplantation (n = 4) a thin-section spiral computed tomography of the chest was performed. The tracheobronchial system and the introduced metallic stents were visualized using a color-coded surface rendering method. The remaining thoracic structures were visualized using a volume rendering method. For virtual bronchoscopy, the tracheobronchial system was visualized using a triangle surface model, a shaded-surface model and a transparent shaded-surface model. RESULTS: The hybrid 3D visualization uses the advantages of both the color-coded surface and volume rendering methods and facilitates a clear representation of the tracheobronchial system and the complex topographical relationship of morphological and pathological changes without loss of diagnostic information. Performing virtual bronchoscopy with the transparent shaded-surface model facilitates a reasonable to optimal, simultaneous visualization and assessment of the surface structure of the tracheobronchial system and the surrounding mediastinal structures and lesions. CONCLUSIONS: Hybrid rendering relieve the morphological assessment of anatomical and pathological changes without the need for time-consuming detailed analysis and presentation of source images. Performing virtual bronchoscopy with a transparent shaded-surface model offers a promising alternative to flexible fiberoptic bronchoscopy.

Anastomosis, Surgical↗
PubMedDate not supplied

Functional results after laparoscopic rectopexy for rectal prolapse.

We investigated the functional results after laparoscopic rectopexy for rectal prolapse in 29 patients at least 12 months postoperatively. Twenty patients were evaluated completely pre- and postoperatively (median 22 months postoperatively, range 12 to 54 months). Six patients were interviewed by telephone, two patients were lost to follow-up, and one patient died of causes unrelated to rectal prolapse. Patients underwent a proctologic examination, anoscopy, rigid sigmoidoscopy, fluoroscopic defecography, and anorectal manometry pre- and postoperatively, and an additional standardized interview postoperatively. Anorectal manometry showed a significant increase in maximum anal resting and squeeze pressures postoperatively (resting pressure 72 +/- 8 vs. 95 +/- 13 mm Hg, pre- vs. postoperatively; P = 0.046; squeeze pressure 105 +/- 17 vs. 142 +/- 19 mm Hg, pre- vs. postoperatively; P = 0.035), and continence improved postoperatively (Wexner incontinence score 6.0 +/- 1.0 vs. 3.9 +/- 0.8 pre- vs. postoperatively, P = 0.02). Twenty (77%) of 26 patients were satisfied with the operative result, but functional morbidity was observed in four patients, with two patients complaining of severe evacuation problems. Rectal prolapse recurred in one patient 42 months postoperatively (recurrence rate 1 [3.8%] of 26 patients). Functional results were very similar to those obtained after open rectopexy, with symptoms of prolapse and incontinence improved in the great majority of patients.

Adult↗