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Biomedical subjects

Mathias Langer

Publications and source records attributed to Mathias Langer.

At least 37 records · Page 2Linked to original sources
PubMed2005

CT in acute perforated sigmoid diverticulitis.

BACKGROUND: To assess the value of computed tomography (CT) in patients with acute perforated sigmoid diverticulitis in correlation with the Hinchey classification of perforated diverticular disease. METHODS: Thirty patients with acute perforated sigmoid diverticulitis underwent computed tomography prior to surgery. Computed tomography scans were compared with the surgical and histopathological reports, utilizing the Hinchey classification. RESULTS: In 28 of the 30 (93%) patients examined, the Hinchey stage was correctly determined by means of computed tomography. One patient with Hinchey stage IV was falsely classified as Hinchey stage III, and one patient with Hinchey stage III as Hinchey stage II. Computed tomography revealed 12 out of 14 (86%) patients with perforation sites and 3 out of 3 (100%) patients with contained perforation. In one of 17 (6%) patients with surgically or histopathologically proven perforation or contained perforation, a bowel wall discontinuity was revealed by computed tomography. In 6 of the 17 (35%) patients with surgical or histopathological perforation or contained perforation, extraluminal contrast material was detected by computed tomography. CONCLUSIONS: Computed tomography is a valuable imaging tool for determining the degree of acute perforated sigmoid diverticulitis, by means of which patients can be stratified according to the severity of the disease; furthermore, this tool is of assistance in surgical planning.

Acute Disease↗
PubMed2005

Differentiation of perianal fistulas with digital subtraction magnetic resonance fistulography.

BACKGROUND: Pelvic magnetic resonance imaging (MRI) is accurate in identifying perianal fistulas. The exact visualization of fistulous tracts and concomitant abscesses determine the type of treatment. To improve the detection of perianal fistulas, we studied digital subtraction MR-fistulography for tissue differentiation based on signal intensity measurements. METHODS: This study included 75 patients with the clinical diagnosis of perianal fistula. All patients were analyzed by a thin-slice, high-resolution, fast low-angle shot 3-dimensional sequence in the axial plane before and after intravenous injection of gadobenate dimeglumine, followed by image subtraction. Operator-defined regions of interest were used to calculate signal intensities of the inflamed fibrous walls of fistulas, the common femoral artery, the internal and external sphincter muscles, and the gluteus muscle. The fistulas were classified according to Parks classification. RESULTS: Based on signal intensity measurements in 75 patients with perianal fistulas, diagnosed by digital subtraction MR-fistulography, a significant differentiation between fistulous tracts and anatomic structures was possible. MRI identified 116 perianal fistulas (34 intersphincteric, 33 transsphincteric, 10 suprasphincteric, and 39 extrasphincteric) and 35 abscesses. CONCLUSIONS: Digital subtraction MR-fistulography is a new, promising, noninvasive imaging technique for the detection of perianal fistulas and abscesses.

Adolescent↗
PubMed2005

High-resolution MRI in giant cell arteritis: imaging of the wall of the superficial temporal artery.

OBJECTIVE: This study investigated the hypothesis that high-resolution MRI can reveal mural inflammatory changes of the superficial temporal artery in giant cell arteritis (GCA). SUBJECTS AND METHODS: MRI of the temporal artery of 20 patients with suspected GCA was performed on a 1.5-T scanner using a dedicated eight-element phased-array head coil. Contrast-enhanced multislice T1-weighted spin-echo sequences were acquired perpendicular to the orientation of the vessel, with a submillimeter spatial resolution of 0.2 x 0.3 mm and a slice thickness of 3 mm. Mural thickness and lumen diameter of the temporal artery were measured, and mural contrast enhancement was graded on a four-point scale by two radiologists. For all patients, the MRI results were compared with the findings of clinical examination and laboratory tests. In addition, biopsy samples of the temporal artery were taken from 16 of these patients. RESULTS: MRI sharply demonstrated the superficial temporal artery, allowing an evaluation of its lumen and wall. Seventeen patients were GCA-positive according to criteria of the American College of Rheumatology. Of these 17, 16 had true-positive MRI findings and one had false-negative MRI findings. The 3 patients who were GCA-negative according to the American College of Rheumatology criteria had true-negative MRI findings. The mean thickness of the vessel wall and the lumen diameter were 0.88 +/- 0.23 mm and 0.78 +/- 0.29 mm, respectively, in GCA-positive patients and 0.57 +/- 0.25 mm and 0.7 +/- 0.1 mm, respectively, in GCA-negative patients. CONCLUSION: High-resolution contrast-enhanced MRI of the temporal artery allowed visualization of the temporal artery and evaluation of possible inflammation of the vessel wall. Our initial results with this noninvasive technique agreed well with histologic results and with the clinical criteria of the American College of Rheumatology.

Aged↗
PubMed2004

[CT and MRI in the differential diagnosis of lesions of the adrenal gland].

Adrenal gland tumors are often incidental findings during imaging of the upper abdomen. In the majority of cases, benign adrenal gland tumors, especially nonfunctioning adenomas, are diagnosed, although the evaluation of dignity is essential in order to avoid unnecessary biopsy and tumor extirpation. Lipid-containing adrenocortical adenomas and nonadenomas can be differentiated with high diagnostic accuracy and specificity by computed tomography (CT) and magnetic resonance imaging (MRI). The fat content of these lesions can be correlated with CT attenuation values or with signal decrease in chemical shift imaging in MRI. Furthermore, low-fat adenomas can be distinguished from nonadenomas with delayed contrast enhancement and washout characterization. For the differentiation of non-fat-containing nonadenomas (metastases, lymphoma, pheochromocytoma, and inflammatory processes), morphological imaging criteria in CT and MRI (signal alterations, contrast media enhancement), clinical signs and laboratory test are essential in order to establish the diagnosis. The localization of functioning adenomas can be easily performed with CT and MRI. Both imaging techniques reveal typical findings of lesions-like cysts and myelolipomas.

Adenoma↗
PubMed2004

Development of a new intravascular low-profile device for exclusion of aortic aneurysm: an experimental pilot study.

PURPOSE: To present a new intravascular device for the treatment of aorto-iliac aneurysms. METHODS: This new device was tested in five dogs with abdominal aortic aneurysm created experimentally by over-dilation of a balloon-expandable stent with a 16 or 18 mm wide PTA balloon catheter. The design of the device is based on a self-expanding aortic stent which consists of two stretchable circular frames filled with a textile Dacron mesh membrane that is suspended horizontally into the infrarenal abdominal aorta proximally to the aneurysm. The frames are part of a preshaped double helical structure that is introduced longitudinally through a catheter in a parallel fashion and forming the desired shape at the vessel site to be occluded. Two iliac stent-grafts are introduced in a low-profile status through the membrane sealing the aneurysm sac and holding the stent-grafts in place. After stent-graft expansion, a new bifurcation located more proximally than the natural one is created. The follow-up of the dogs was performed clinically and angiographically, and specimens were evaluated histomorphologically. RESULTS: The membrane device can be introduced through a 9 Fr vascular sheath. Technical success was achieved in four of five dogs. Nine of ten stent-grafts could be fixed securely within the membrane, thus preventing dislocation. Aneurysms were excluded immediately, and blood flow to the external iliac arteries was restored by the stent-grafts. At 6-9 months follow-up of technically successful implanted devices, there were no endoleaks, no migration, no stenoses at contact sites between the implant material and vascular wall, and no stenosis or occlusion of the stent-grafts. At microscopic evaluation, the interspace between the membranes was filled with thrombotic material, thus ensuring exclusion of the aneurysm. CONCLUSION: This new device was found to be flexible, low profile and useful in excluding abdominal aortic aneurysm in the experimental setting.

Animals↗
PubMed2004

Assessment of anal fistulas with high-resolution subtraction MR-fistulography: comparison with surgical findings.

PURPOSE: To investigate a new MR-imaging protocol defined as subtraction MR-fistulography for the detection of fistula-in-ano. MATERIALS AND METHODS: A total of 36 patients (18 men, 18 women) with the clinical diagnosis of anal fistula or abscess who were scheduled for surgical exploration were preoperatively imaged at 1.5 T in the supine position; coronal STIR sequences and axial T1-weighted three-dimensional FLASH sequences before and after intravenous injection of gadobenate dimeglumine (Gd-BOPTA) were obtained. Image subtraction was routinely used. The image findings were compared with the findings at surgical exploration according to a uniform classification system. RESULTS: A total of 46 fistulas were seen on subtraction MR-fistulography, whereas surgery described 41 fistulas. MRI and surgery concordantly depicted a total number of 40 fistulas, six fistulas were only described by MRI, and one fistula was only seen during surgery. A total of 27 abscesses were detected with MRI, compared to 22 during surgery. A total of 22 abscesses were concordantly diagnosed. Complete agreement between subtraction MR-fistulography and surgery occurred in 32 (89%) of the 36 patients. The four patients in whom both procedures disagreed had complex anal sepsis with multiple fistulas and/or abscesses due to Crohn disease. CONCLUSION: High-resolution subtraction MR-fistulography is an important complement to surgical exploration and especially suitable for investigating complex anal sepsis.

Adolescent↗
PubMed2004

High-resolution CT imaging of the lung for patients with primary Sjogren's syndrome.

PURPOSE: To assess pulmonary abnormalities in patients with primary Sjogren's syndrome (PSS) using high-resolution computed tomography (HRCT). MATERIAL AND METHODS: The HRCT scans of 24 patients with the diagnosis PSS were retrospectively reviewed regarding the presence, extension and distribution of 16 pathological findings. RESULTS: Nineteen patients (79.2%) showed pathological findings and in five patients (21.8%) the HRCT scan was judged to be normal. A predominance of abnormalities in the lower lobes and subpleural areas was detected. The following pathologies were found: bronchiectasis, thin-walled cysts and small pulmonary nodules (46.2%), ground-glass attenuation and emphysema (37.8%), interlobular-septal thickening (29.4%), honeycombing (25.2%), bronchial wall thickening, tree-in-bud pattern (21.0%), mosaic perfusion (16.8%), architectural distortion (12.6%). Airspace consolidation, air trapping, large nodules (10-30mm) and masses (>30mm), mediastinal lymph node enlargement (>15mm) and free pleural fluid were seen each in 4.2%. In 7 of the 11 patients with thin-walled cysts areas of ground-glass attenuation were detected. CONCLUSION: HRCT seems is contributive to the characterization of the wide variety of lung abnormalities in PSS. Airway disease alone or in association with the presence of varying degrees of interstitial disease represents the main findings in accordance with earlier reports. Unexpectedly, almost half of the patients had thin-walled cysts on the HRCT scans, which etiology is unclear but could be associated with areas of ground-glass attenuation indicating LIP.

Adult↗
PubMed2003

Radiological findings in Boerhaave's syndrome.

The aim was to define the diagnostic value of chest radiography, esophagography, and computed tomography (CT) in patients with Boerhaave's syndrome. CT findings in 14 patients (11 male, 3 female; mean age: 60 years; median age: 66 years; age range: 36-78 years) with spontaneous esophageal perforation were retrospectively reviewed and compared to those of esophagography ( n=11) and chest radiography ( n=14). In six patients unenhanced CT scans were available; in ten patients (2/10 patients had an unenhanced CT before) a contrast-enhanced CT was performed as an emergency investigation. In 5/14 patients additional oral contrast medium was given. Chest radiography revealed pleural effusions in 9/14 and infiltrates in 9/14 patients. Pneumothorax and pneumopericardium were observed in two patients each. Pneumomediastinum was seen in three patients. Two chest radiographs were normal. Esophagography performed in 11 patients demonstrated contrast medium extravasation at a supradiaphragmatic level in seven patients, indicating esophageal perforation with esophagopleural fistula, and a submucosal contrast medium collection in four cases. Unenhanced CT scans revealed four intramural hematomas with typical localization. Unenhanced and contrast-enhanced CT demonstrated periesophageal air collections indicating esophageal perforation in all patients. Pleural effusions were seen in 11/14 and infiltrates in 8/14 patients. Contrast medium extravasation was observed in 5/14 patients, whereas a thickening of the esophageal wall was depicted in 11/14 patients. Periaortic air tracks ( n=7), pneumothorax ( n=3), pneumomediastinum ( n=6), and mediastinal fluid collections ( n=7) were depicted in CT. By demonstrating periesophageal air tracks suggestive of esophageal perforation, CT reveals the decisive criteria for diagnosing Boerhaave's syndrome and should therefore be performed in the diagnostic work-up of patients in whom this syndrome is part of the differential diagnosis.

Journal Article↗
PubMed2003

Computed tomography in gastrointestinal stromal tumors.

The aim of this study was to define the imaging characteristics of primary and recurrent gastrointestinal stromal tumors (GIST) in computed tomography with respect to the tumor size. Computed tomography was performed in 35 patients with histologically confirmed gastrointestinal stromal tumors and analyzed retrospectively by two experienced and independent radiologist. The following morphologic tumor characteristics of primary ( n=20) and ( n=16) recurrent tumors were evaluated according to tumor size, shape, homogeneity, density compared with liver, contrast enhancement, presence of calcifications, ulcerations, fistula or distant metastases and the anatomical relationship to the intestinal wall, and the infiltration of adjacent visceral organs. Small GIST (<5 cm) showed a sharp tumor margin with homogeneous density and structure on unenhanced and contrast-enhanced images, and were characterized by an intraluminal tumor growth. Intermediate sized GIST (>5-10 cm) demonstrated an irregular shape, inhomogeneous density on unenhanced and contrast-enhanced images, a combined intra- and extraluminal tumor growth with aggressive findings, and infiltration of adjacent organs in 9 primary diagnosed and 2 recurrent tumors. Large GIST (>10 cm), which were observed in 8 primary tumors and 11 recurrent tumors, showed an irregular margin with inhomogeneous density and aggressive findings, and were characterized by signs of malignancy such as distant and peritoneal metastases. Small recurrent tumors had a similar appearance as compared with large primary tumors. Computed tomography gives additional information with respect to the relationship of gastrointestinal stromal tumor to the gastrointestinal wall and surrounding organs, and it detects distant metastasis. Primary and recurrent GIST demonstrate characteristic CT imaging features which are related to tumor size. Aggressive findings and signs of malignancy are found in larger tumors and in recurrent disease. Computed tomography is useful in detection and characterization of primary and recurrent tumors with regard to tumor growth pattern, tumor size, and varied appearances of gastrointestinal stromal tumors, and indirectly gives hints regarding dignity and therefore prognostic outcome.

Female↗
PubMed2003

Ectopic thyroid gland in the porta hepatis and lingua.

A rare case of an ectopic thyroid gland in the porta hepatis and in the tongue in an asymptomatic euthyroid 24-year-old woman is reported. A solitary inhomogeneous, hypoechogenic and hyperechogenic mass in the porta hepatis was accidentally discovered by ultrasonography. Subsequent computed tomography demonstrated a heterogeneous, well-defined tumor with small calcifications without signs of environmental invasion. A hemangioma and focal nodular hyperplasia were excluded by blood pool and hepatobiliary scintigraphy. Surprisingly, fine-needle aspiration cytology revealed normal thyroid tissue. (123)I-scintigraphy confirmed the presence of ectopic dual thyroid tissue in the hepatic porta and lingua. At clinical inspection the lingual thyroid gland was palpable and visible, and appeared solid and spheroidal. The subhepatic, ectopic thyroid mass was resected. Postoperatively, thyroid hormone replacement was started to prevent an enlargement of the lingual thyroid. Today, 4 years after surgery, the patient remains euthyroid.

Adult↗
PubMed2003

Amorphous silicon, flat-panel, x-ray detector versus storage phosphor-based computed radiography: contrast-detail phantom study at different tube voltages and detector entrance doses.

RATIONALE AND OBJECTIVES: Evaluation of the contrast-detail performance of an active-matrix flat-panel x-ray detector in comparison with a storage phosphor system with special regard to the potential of dose reduction. METHODS: A digital x-ray detector based on cesium iodide (CsI) and amorphous silicon (a-Si) technology was compared with a fifth-generation storage phosphor system. A lucite plate with 36 drilled holes of varying diameters and depths was used as contrast-detail phantom. At 45 kVp, 70 kVp, and 113 kVp, images at 8 different detector entrance doses ranging between 0.3 microGy and 40 microGy were obtained. On soft-copy displays, 3 masked observers evaluated the detectability of each aperture in each image according to a 5-point scale. The mean sum scores of corresponding images were compared. RESULTS: For all tube voltages and detector entrance doses, the images obtained with the CsI/a-Si detector resulted in better observer contrast-detail performance as compared with the images of the storage phosphor system. The CsI/a-Si system allowed a calculated dose reduction of 39% at 45 kVp, 68% at 70 kVp, and 81% at 113 kVp as compared with the storage phosphor system, without loss of contrast-detail detectability. CONCLUSIONS: Under the conditions of the chosen experimental design, the CsI/a-Si system provided a superior contrast-detail performance as compared with the storage phosphor system. The potential of dose reduction increased with rising tube voltage.

Cesium↗
PubMed2003

Comparison of the detectability of high- and low-contrast details on a TFT screen and a CRT screen designed for radiologic diagnosis.

RATIONALE AND OBJECTIVES: To evaluate the detection rate of fine details of a new thin-film transistor (TFT) grayscale monitor designed for radiologic diagnosis, compared with a type of cathode ray tube (CRT) screen used routinely for diagnostic radiology. METHODS: Fifteen radiographs of a statistical phantom presenting low- and high-contrast details were obtained and read out with an Agfa ADC compact storage phosphor system. Each radiograph presented 60 high-density (high-contrast) and 60 low-density (low-contrast) test bodies. Approximately half the test bodies contained holes with different diameters. Observers were asked to detect the presence or absence of a hole in the test body on a 5-point confidence range. The total of 1800 test bodies was reviewed by 5 radiologists on the TFT monitor (20.8 inches; 1536 x 2048 pixels; maximum luminance, 650 cd/m2; contrast, 600:1) and the CRT monitor (21 inches; P45 Phosphor; 2048 x 2560 pixels operated at 1728 x 2304 pixels; maximum luminance, 600 cd/m2; contrast, 300:1). The data were analyzed by receiver-operator characteristic analysis. RESULTS: For high-contrast details, the mean area under the curve rated 0.9336 for the TFT monitor and 0.9312 for the CRT monitor. For low-contrast details, the mean area under the curve rated 0.9189 for the TFT monitor and 0.9224 for the CRT monitor. At P <or= 0.05, no statistically significant difference could be detected between the 2 observational modalities for both (holes in high- and low-contrast disks) types of artifacts. CONCLUSIONS: The TFT screen performs as well as CRT monitors for the detection of fine details in both high- and low-contrast environments. Further studies with images derived from clinical routine are necessary before safely using TFT monitors in clinical practice.

Phantoms, Imaging↗
PubMed2003

MR imaging of autopsy-proved paraneoplastic limbic encephalitis in non-Hodgkin lymphoma.

We report the case of a 26-year-old man with precursor T-cell acute lymphoblastic leukemia who developed paraneoplastic limbic encephalitis that was diagnosed on the basis of MR imaging findings and was proved post mortem. In our MR imaging studies, fluid-attenuated inversion recovery images and diffusion-weighted echo-planar images clearly depicted bilateral involvement of the medial temporal lobes and multifocal involvement of the brain, whereas T2-weighted turbo spin-echo images failed to show the changes.

Adult↗